Pilot

• Episode 1

Brilliant physicist roommates Leonard and Sheldon meet their new neighbor Penny, who begins by showing them that as much as they know about science, they know little about actual living.

The Big Bran Hypothesis

• Episode 2

Leonard volunteers to sign for a package in an attempt to make a good impression on Penny, but when he enlists Sheldon for help, his attempt at chivalry goes terribly awry.

The Fuzzy Boots Corollary

• Episode 3

Leonard asks a woman out after he finds out that Penny is seeing someone.

The Luminous Fish Effect

• Episode 4

Getting fired forces Sheldon to explore what life has to offer outside physics, leaving Leonard to take drastic action to snap his friend out of his funk.

The Hamburger Postulate

• Episode 5

Sensing that he's wasting his time on Penny, Leonard ends up making a connection with Leslie.

The Middle-Earth Paradigm

• Episode 6

Penny hosts a Hallowe'en party, putting Leonard, Sheldon, Wolowitz, and Koothrappali through a new test of their social skills.

The Dumpling Paradox

• Episode 7

With Wolowitz AWOL with one of her friends, Penny's recruited to fill in for him on the guys' Halo team.

The Grasshopper Experiment

• Episode 8

Raj's parents set him up on a blind date, but just when he discovers he can talk to her, she shows interest in Sheldon.

The Cooper-Hofstadter Polarization

• Episode 9

When they're invited to present at a physics conference, Sheldon's reluctance to share the credit leads to a tiff between him and Leonard. Penny's intervention only exacerbates the situation.

The Loobenfeld Decay

• Episode 10

Leonard and Sheldon each lie to avoid seeing Penny's concert, but Sheldon's is a bit too complicated for his own good.

The Pancake Batter Anomaly

• Episode 11

With his friends knowing how sour he acts when he’s sick, Sheldon is nursed by Penny, who hasn't got a clue what she's in for.

The Jerusalem Duality

• Episode 12

With Sheldon rattled over meeting Dennis, a 15-year-old physicist who's smarter than he, Leonard helps him look for a way to debunk Dennis's research.

The Bat Jar Conjecture

• Episode 13

Sheldon finds himself booted from the gang's Physics Bowl team and replaced with Leslie, so he forms his own team hoping to prove he's superior.

The Nerdvana Annihilation

• Episode 14

When delivery of another collectible leads to Penny's lashing out at Leonard, he decides it's time to give up his habit, much to his friends' protestation.

The Pork Chop Indeterminacy

• Episode 15

The rest of the gang fall for Sheldon's twin sister and Leonard's plan to win her heart is derailed when Sheldon declares he'll be the one to decide who can date her.

The Peanut Reaction

• Episode 16

Penny wants to throw a surprise party for Leonard, but Sheldon's indulgence at an electronics store throws her off-track.

The Tangerine Factor

• Episode 17

Penny's break-up spurs Leonard to summon the courage to ask her out. Both go to Sheldon for advice on their upcoming date.

The Bad Fish Paradigm

• Episode 1

Penny's first date with Leonard goes awry and she finds Sheldon to be an unwilling confidant.

The Codpiece Topology

• Episode 2

A jealous Leonard reacts to Penny's new guy by rebounding with Leslie.

The Barbarian Sublimation

• Episode 3

Sheldon creates a monster when he introduces Penny to online gaming.

The Griffin Equivalency

• Episode 4

Raj gets an inflated ego and makes a play for Penny after being referenced in a magazine article.

The Euclid Alternative

• Episode 5

Leonard and his friends stage an intervention to force Sheldon to face his fear of driving.

The Cooper-Nowitzki Theorem

• Episode 6

Sheldon and the gang are confused when a young grad student is attracted to him.

The Panty Piñata Polarization

• Episode 7

When Sheldon bans Penny from the apartment for numerous minor infractions, she decides to retaliate.

The Lizard-Spock Expansion

• Episode 8

Leonard inadvertently steals away the new woman Wolowitz thinks is the love of his life.

The White Asparagus Triangulation

• Episode 9

Sheldon is thrilled when Leonard starts dating a woman who meets Sheldon's stringent standards.

The Vartabedian Conundrum

• Episode 10

Leonard asks Penny for advice when his new relationship starts moving too fast.

The Bath Item Gift Hypothesis

• Episode 11

Penny starts dating Leonard's handsome colleague; Leonard and his friends are tortured by Sheldon's obsession with gift-giving etiquette.

The Killer Robot Instability

• Episode 12

Penny's criticism of Wolowitz's romantic life pushes him into depression and he goes AWOL for a fighting robot battle the rest of guys are depending on him for.

The Friendship Algorithm

• Episode 13

Sheldon creates a scientific procedure for making friends.

The Financial Permeability

• Episode 14

Sheldon's solution to Penny's financial difficulty leads to a confrontation between Leonard and Penny's ex-boyfriend.

The Maternal Capacitance

• Episode 15

Leonard and Penny are drawn together after a disastrous visit from Leonard's mother.

The Cushion Saturation

• Episode 16

A paintball game leads to a fight between Sheldon and Penny and romance for Leslie and Wolowitz.

The Terminator Decoupling

• Episode 17

Leonard, Sheldon and Wolowitz are ecstatic to learn that a famous science-fiction actress (Summer Glau) is on board the train they are taking to San Francisco.

The Work Song Nanocluster

• Episode 18

Penny's home business turns into a complete nightmare when Sheldon takes over.

The Dead Hooker Juxtaposition

• Episode 19

Penny squares off with a new beautiful female neighbor who may become the building's 'new Penny'.

The Hofstadter Isotope

• Episode 20

A fellow comic book enthusiast's hitting on Penny leads to Leonard and Howard going to a bar's Ladies' Night.

The Vegas Renormalization

• Episode 21

Leonard and Koothrappali escort a heartbroken Wolowitz to Las Vegas. Sheldon becomes locked out of his apartment so must stay with Penny.

The Classified Materials Turbulence

• Episode 22

Penny's second date with Stuart sees her making a comment that gives Leonard new hope for a relationship with her. Wolowitz realizes there's a crucial error in a NASA project he's working on.

The Monopolar Expedition

• Episode 23

The guys' plan to work over the summer at the North Pole makes Penny revaluate her feelings for Leonard.

The Electric Can Opener Fluctuation

• Episode 1

When Sheldon learns that the guys tampered with his expedition data he got from the arctic, he leaves to Texas in disgrace. This results in the guys following him, which threatens Leonard's hope for some romantic time with Penny and the guys' friendship with Sheldon.

The Jiminy Conjecture

• Episode 2

Leonard and Penny struggle to recover from an awkward first hookup while Sheldon and Howard stake their best comic books on a bet to determine the species of a cricket.

The Gothowitz Deviation

• Episode 3

Howard and Raj visit a Goth nightclub to pick up women while Sheldon attempts to build a better Penny using chocolate-based behavior modification.

The Pirate Solution

• Episode 4

Raj must find a new job or be sent back to India, but Sheldon has a solution, which leaves Leonard and Penny dealing with Howard as a third wheel.

The Creepy Candy Coating Corollary

• Episode 5

After overhearing that Wil Wheaton is entering a trading-card competition, Sheldon decides to enter it himself. Meanwhile, Penny sets up one of her friends on a date with Wolowitz.

The Cornhusker Vortex

• Episode 6

Sheldon becomes Leonard's teacher in order to understand football, while an incident with flying a kite threatens Howard and Raj's friendship.

The Guitarist Amplification

• Episode 7

A squabble between Leonard and Penny sees Sheldon playing mediator, though out of his own incovenience from the sitiation rather than altruism.

The Adhesive Duck Deficiency

• Episode 8

With Leonard, Howard and Raj away camping in the desert, an injured Penny has only Sheldon to rely on.

The Vengeance Formulation

• Episode 9

After he's humiliated on National Public Radio, Sheldon vows to destroy Kripke, while Wolowitz tries not to destroy his new relationship with Bernadette.

The Gorilla Experiment

• Episode 10

Penny gets help from Sheldon in order to understand what Leonard's work is, while Wolowitz develops a jealousy when Leonard starts hanging out with his new girlfriend.

The Maternal Congruence

• Episode 11

A Christmas visit from his mother has Leonard discovering she's kept a lot of news from him that she shares with Sheldon and worrying if she'll approve of his romance with Penny.

The Psychic Vortex

• Episode 12

Leonard is aghast to find out a secret of Penny's: she believes in psychics. Meanwhile, Sheldon tries to assist Koothrappali in picking up a girl at a university mixer.

The Bozeman Reaction

• Episode 13

When their apartment is robbed, Leonard and Sheldon turn to their friends to create a state-of-the-art security system.

The Einstein Approximation

• Episode 14

Sheldon's search for the answer to a physics problem leads him to work at the Cheesecake Factory with Penny.

The Large Hadron Collision

• Episode 15

Leonard can only bring one guest on a trip to see CERN's Large Hadron Collider (the world's largest and highest energy particle accelerator) in Switzerland on Valentine's Day.

The Excelsior Acquisition

• Episode 16

Sheldon winds up in traffic court when he gets a ticket because of Penny.

The Precious Fragmentation

• Episode 17

When the guys find a ring from 'The Lord of the Rings' at a garage sale, it threatens to tear them apart.

The Pants Alternative

• Episode 18

Sheldon's friends come to his aid when his fear of public speaking stands between him and a coveted award.

The Wheaton Recurrence

• Episode 19

A fight between Leonard and Penny threatens their relationship, while Sheldon battles Wil Wheaton in bowling.

The Spaghetti Catalyst

• Episode 20

When Leonard and Penny aren't speaking, Sheldon goes to extremes to keep them both happy.

The Plimpton Stimulation

• Episode 21

Leonard and Sheldon compete for the attention of a famous female physicist.

The Staircase Implementation

• Episode 22

Leonard tells Penny about how he met Sheldon for the first time...and what happened to the elevator.

The Lunar Excitation

• Episode 23

While Penny worries that dating Leonard has ruined her for normal guys, Wolowitz and Koothrappali search for Sheldon's perfect match online.

The Robotic Manipulation

• Episode 1

Penny tags along on Sheldon's first ever date; Wolowitz finds a new use for a robotic arm.

The Cruciferous Vegetable Amplification

• Episode 2

Realizing he will not live long enough to download his consciousness into a robot body, Sheldon tries to extend his life span.

The Zazzy Substitution

• Episode 3

The guys are concerned as Sheldon searches for an alternative to human companionship.

The Hot Troll Deviation

• Episode 4

An embarrassing secret of Wolowitz's comes to light, while Sheldon and Raj have a small war at work.

The Desperation Emanation

• Episode 5

Leonard realizes he’s the only one without a girlfriend, while Sheldon wants to get rid of his.

The Irish Pub Formulation

• Episode 6

Leonard keeps an affair a secret from Sheldon, Howard and Raj.

The Apology Insufficiency

• Episode 7

Sheldon's answers during an FBI interview put Wolowitz's security clearance in jeopardy.

The 21-Second Excitation

• Episode 8

While the guys camp in line for a long-awaited movie screening, Penny and Bernadette invite Amy to her first slumber party.

The Boyfriend Complexity

• Episode 9

Penny asks Leonard to lie to her father, while Howard, Raj and Bernadette pull an all-nighter at a telescope.

The Alien Parasite Hypothesis

• Episode 10

Amy finds she has sexual feelings for Penny's ex, while Koothrappali and Wolowitz try to prove who would be the better superhero.

The Justice League Recombination

• Episode 11

The guys find a "super" use for Penny's new boyfriend, Zack, when they enter a costume contest as the Justice League.

The Bus Pants Utilization

• Episode 12

Leonard's idea for a smartphone app derails his friendship with Sheldon.

The Love Car Displacement

• Episode 13

Bernadette runs into her ex-boyfriend while attending a science event with Wolowitz.

The Thespian Catalyst

• Episode 14

Hoping it will make him a better teacher, Sheldon has Penny give him acting lessons. Raj has fantasies about a friend's girlfriend.

The Benefactor Factor

• Episode 15

A wealthy donor to the university makes Leonard consider how far he's willing to go for the sake of science.

The Cohabitation Formulation

• Episode 16

As Wolowitz contemplates taking things with Bernadette to the next level, Leonard rekindles his relationship with Raj's sister.

The Toast Derivation

• Episode 17

Sheldon becomes concerned when everybody begins to hang out at Raj's apartment and discovers Leonard is the center of the group.

The Prestidigitation Approximation

• Episode 18

Sheldon is baffled by Wolowitz's magic trick. Meanwhile, Leonard realizes dating Priya may make it impossible to continue being friends with Penny.

The Zarnecki Incursion

• Episode 19

Sheldon's World of Warcraft online game account is hacked and he is determined to find out who did it. Also Penny shares some girl talk with her friends about Leonard and his new girlfriend.

The Herb Garden Germination

• Episode 20

Sheldon and Amy decide to start several rumors about the others as a test. Meanwhile, Howard takes his relationship with Bernadette to even higher level.

The Agreement Dissection

• Episode 21

When Leonard spends too much time in the shower with Priya, Sheldon charges Leonard with two violations of the roommate agreement.

The Wildebeest Implementation

• Episode 22

Raj attempts to cure his social anxiety disorder while Penny uses Bernadette to spy on Leonard and his girlfriend.

The Engagement Reaction

• Episode 23

When Howard finally breaks the news to his mom that he's engaged to Bernadette, it lands her in the hospital.

The Roommate Transmogrification

• Episode 24

When Bernadette receives her PhD, Wolowitz feels emasculated. Raj and Leonard swap places and Penny does something she regrets.

The Skank Reflex Analysis

• Episode 1

Penny is worried with how damaged her friendship with the guys will be in the aftermath of her sleeping with Raj while Sheldon becomes the leader of the paintball team.

The Infestation Hypothesis

• Episode 2

A fight between Sheldon and Penny leaves Amy caught in the middle, while Leonard tries to spice up his long-distance relationship with Priya.

The Pulled Groin Extrapolation

• Episode 3

Leonard and Amy get to know each other better, while Howard and Bernadette spend the weekend with Mrs. Wolowitz.

The Wiggly Finger Catalyst

• Episode 4

Penny plays Matchmaker for Raj, which results in him finding a girl he is comfortable talking to.

The Russian Rocket Reaction

• Episode 5

Sheldon and Leonard get invited to a party at Wil Wheaton's house, and Howard gets an out-of-this-world opportunity.

The Rhinitis Revelation

• Episode 6

Sheldon's mother, Mary Cooper, comes to visit, but Sheldon is annoyed that she spends time with the rest of the gang instead of catering to his every demand.

The Good Guy Fluctuation

• Episode 7

A cute comic book artist puts Leonard and Priya’s relationship to the test, while Sheldon tries to scare the guys for Halloween.

The Isolation Permutation

• Episode 8

Amy becomes heartbroken when she discovers that Penny and Bernadette went wedding dress shopping without her.

The Ornithophobia Diffusion

• Episode 9

Leonard and Penny try hanging out as friends on a 'non-date', but end up purposely ruining each others chances with perspective dates. Meanwhile, Sheldon enlists the help of Bernadette and Amy to overcome his fear of birds.

The Flaming Spittoon Acquisition

• Episode 10

Sheldon becomes jealous when Stuart asks Amy for a date.

The Speckerman Recurrence

• Episode 11

Leonard must face his fears after being contacted by his high school tormentor.

The Shiny Trinket Maneuver

• Episode 12

Sheldon gets in trouble with Amy when he isn't impressed by her recent accomplishment, and Howard must come to grips with Bernadette's dislike of children.

The Recombination Hypothesis

• Episode 13

Leonard, having broken up with Priya, asks Penny out to a spur-of the-moment romantic dinner for two.

The Beta Test Initiation

• Episode 14

Leonard and Penny deal with the idea of starting a relationship again and Raj finally finds a 'woman' he can talk to without being drunk, in the form of Siri on his new phone.

The Friendship Contraction

• Episode 15

Sheldon's selfish demands force Leonard to reconsider their friendship. Meanwhile, Wolowitz tries to pick his astronaut nickname.

The Vacation Solution

• Episode 16

When Sheldon is forced to take his vacation, he goes to work with Amy in her neurobiology lab.

The Rothman Disintegration

• Episode 17

Penny is horrified when Amy gives her a gift: a huge, quite horrible painting of the two of them. With no good way to avoid displaying it, she only hangs it up when Amy is over.

The Werewolf Transformation

• Episode 18

Sheldon becomes agitated when his regular barber is out sick. Astronaut training causes Howard to reconsider wanting to go into space.

The Weekend Vortex

• Episode 19

Sheldon must choose between joining Amy at her aunt's birthday party or playing videogames all weekend with the guys.

The Transporter Malfunction

• Episode 20

Penny buys Leonard and Sheldon “Star Trek” collectibles as a thank-you, leading Sheldon to be haunted by Mr. Spock. Meanwhile, Raj decides he has met the 'Future Mrs. Koothrappali' after his parents set him up on a date.

The Hawking Excitation

• Episode 21

When Wolowitz gets to work with Stephen Hawking, Sheldon is willing to do anything to meet his hero.

The Stag Convergence

• Episode 22

After the guys throw Howard a bachelor party, Bernadette reconsiders marrying him after learning about his sexual history.

The Launch Acceleration

• Episode 23

When NASA moves up Howard's mission, he must face his fears and Bernadette's dad, thus putting the wedding plans in jeopardy.

The Countdown Reflection

• Episode 24

The fifth season ends with Howard and Bernadette deciding to get married before his NASA mission, causing the gang to scurry into overdrive in an effort to stage the wedding.

The Date Night Variable

• Episode 1

With his friends on dates, Raj must face his loneliness. Also, Wolowitz is caught in an argument between Bernadette and his mom, even while he’s in space.

The Decoupling Fluctuation

• Episode 2

When Sheldon learns that Penny is thinking about breaking up with Leonard, he tries to intervene. Meanwhile, in space, the other astronauts pick on Howard.

The Higgs Boson Observation

• Episode 3

Amy feels threatened when Sheldon hires a young female assistant, and the pressure of being in space takes its toll on Wolowitz.

The Re-Entry Minimization

• Episode 4

When Wolowitz returns from space, he doesn’t get the hero’s welcome he expected. Meanwhile, Game Night turns into a battle of the sexes.

The Holographic Excitation

• Episode 5

The gang celebrates Halloween at Stuart’s comic book store. Meanwhile, Leonard seduces Penny with science.

The Extract Obliteration

• Episode 6

Sheldon’s relationship with Stephen Hawking is threatened over a game of ‘Words with Friends,’ and Penny secretly enrolls in a class at the local college.

The Habitation Configuration

• Episode 7

Wolowitz struggles with moving out of his mother’s house. Meanwhile, Sheldon is caught in the middle of an argument between Amy and Wil Wheaton.

The 43 Peculiarity

• Episode 8

Raj and Howard try to to figure out why Sheldon disappears at 2:45 every afternoon. Meanwhile, jealousy arises in Penny and Leonard's relationship.

The Parking Spot Escalation

• Episode 9

When the University reassigns Sheldon’s parking spot to Wolowitz, their fight affects the whole gang.

The Fish Guts Displacement

• Episode 10

When Amy gets sick, Sheldon tries to nurse her back to health; Wolowitz and his father-in-law plan a fishing trip.

The Santa Simulation

• Episode 11

During a game, Sheldon revisits Christmas memories. Amy, Penny and Bernadette look for a date for Koothrappali.

The Egg Salad Equivalency

• Episode 12

When Sheldon is accused of sexual harassment, he ends up getting Raj, Leonard and Wolowitz in trouble.

The Bakersfield Expedition

• Episode 13

As the guys don costumes and go on a road trip to a comic book convention, the ladies decide to stay home and try to interpret a comic book.

The Cooper/Kripke Inversion

• Episode 14

Sheldon faces a crisis of confidence when he is forced to work with his nemesis, Barry Kripke; Raj and Howard buy expensive action figures of themselves.

The Spoiler Alert Segmentation

• Episode 15

A fight between Sheldon and Leonard impacts Amy and Penny's living arrangements. while Howard is away, Raj helps Mrs. Wolowitz out.

The Tangible Affection Proof

• Episode 16

The guys search for a perfect Valentine's Day gift for their significant others and Stuart and Raj host a "lonely people" party at the comic book store.

The Monster Isolation

• Episode 17

After a bad date, Koothrappali decides to never leave his apartment. Penny's acting skills impress Sheldon.

The Contractual Obligation Implementation

• Episode 18

Leonard, Sheldon and Wolowitz talk to junior high girls about science-related careers and Raj plans a date with Lucy.

The Closet Reconfiguration

• Episode 19

Howard considers whether or not he should open a letter from his father; Penny and Leonard host a 'grown-up' cocktail party.

The Tenure Turbulence

• Episode 20

The girls get involved when Leonard, Sheldon and Raj compete for tenure at the University.

The Closure Alternative

• Episode 21

Amy tries to help Sheldon get over his compulsive need for closure when one of his favorite TV shows is canceled. Raj discovers a secret about Lucy.

The Proton Resurgence

• Episode 22

Leonard and Sheldon hire the host (Bob Newhart) of their favorite childhood TV show to perform. meanwhile, Bernadette and Howard run into trouble while dog-sitting for Raj's pet.

The Love Spell Potential

• Episode 23

Amy and Sheldon's relationship takes a surprising turn during a game of 'Dungeons & Dragons'. Lucy and Koothrappali have an awkward date.

The Bon Voyage Reaction

• Episode 24

When Leonard receives an exciting opportunity to work overseas, Penny and Sheldon are thrown for a loop.

The Hofstadter Insufficiency

• Episode 1

With Leonard away, Sheldon and Penny spend quality time together sharing intimate secrets. Also, Wolowitz helps Raj get over his ex-girlfriend.

The Deception Verification

• Episode 2

Leonard and Sheldon's friendship is tested; Wolowitz's relationship with his mom causes a threat to his masculinity.

The Scavenger Vortex

• Episode 3

When the entire gang competes in a scavenger hunt designed by Raj, it brings out the best - and worst - in everyone.

The Raiders Minimization

• Episode 4

Beverly Hofstadter writes a psychology book about Leonard which Penny buys and reads. Sheldon wants to ruin something for Amy after she ruins an Indiana Jones movie for him and Raj and Stuart try online dating.

The Workplace Proximity

• Episode 5

Amy starts working at Caltech which causes friction with Sheldon. Howard agrees with Sheldon who mentions this to Bernadette causing a big fight for the Wolowitzes.

The Romance Resonance

• Episode 6

Sheldon's latest scientific breakthrough leaves him feeling like a fraud and a romantic gesture between Howard and Bernadette causes Penny to up her game with Leonard.

The Proton Displacement

• Episode 7

When Professor Proton asks Leonard for help with an experiment, Sheldon retaliates by befriending Proton's rival, Bill Nye.

The Itchy Brain Simulation

• Episode 8

When a mistake comes to light, Sheldon makes Leonard walk a mile in his shoes; Penny decides to confront Raj's ex.

The Thanksgiving Decoupling

• Episode 9

Sheldon protests when the gang drags him to Mrs. Wolowitz’s house for Thanksgiving. Meanwhile, Penny and Leonard must deal with a mistake from her past.

The Discovery Dissipation

• Episode 10

Leonard and Amy help Sheldon cope with the shame he’s feeling after his accidental contribution to science is disproved. Meanwhile, Raj must stay with Howard and Bernadette for a week.

The Cooper Extraction

• Episode 11

While Sheldon is in Texas, the rest of the gang realizes how much he has changed their lives as they decorate the apartment Christmas tree.

The Hesitation Ramification

• Episode 12

When Penny’s big acting break on NCIS is a bust, Leonard struggles to help her, which results in Penny asking Leonard a bold relationship question. Meanwhile, Sheldon tries to learn how to be funny.

The Occupation Recalibration

• Episode 13

Sheldon tries to relax after he is forced to take a vacation. Meanwhile, Leonard struggles to be supportive of Penny after she quits her job, and Bernadette seeks Stuart’s help in replacing one of Howard’s comic books.

The Convention Conundrum

• Episode 14

After the guys can’t get Comic-Con tickets, Sheldon tries to hold his own convention and winds up spending a wild night with James Earl Jones.

The Locomotive Manipulation

• Episode 15

Sheldon and Amy go on a trip to wine country with Howard and Bernadette; Penny and Leonard rush Raj's dog to the vet.

The Table Polarization

• Episode 16

Leonard buys a dining room table and it causes Sheldon to reevaluate the changes in his life. Meanwhile, Wolowitz is offered a chance to go back to space and Bernadette struggles with whether or not to encourage him.

The Friendship Turbulence

• Episode 17

Bernadette tries to negotiate peace between Sheldon and Wolowitz; Penny receives an embarrassing offer and Raj wants Amy to write to a woman on his behalf.

The Mommy Observation

• Episode 18

When Sheldon visits his Mom in Houston, he is forced to confront a new reality. Meanwhile, Raj’s ‘Murder Mystery’ party starts some fights within the gang.

The Indecision Amalgamation

• Episode 19

While Raj is wracked with guilt when he tries to date two women at once, Penny wrestles with whether to take a role in a cheesy movie and Sheldon is torn trying to choose between two gaming systems.

The Relationship Diremption

• Episode 20

Sheldon faces a personal crisis after deciding he’s wasting his time with string theory. Meanwhile, a double date between Raj, Emily and the Wolowitzes ends in embarrassment for Howard.

The Anything Can Happen Recurrence

• Episode 21

To prepare for a date with Emily, Howard acclimatizes Raj to horror movies. Penny and Sheldon are upset when they discover Amy and Bernadette lied to avoid hanging out with them.

The Proton Transmogrification

• Episode 22

As the gang celebrates Star Wars Day, Sheldon discovers he is having difficulty dealing with the death of Professor Proton.

The Gorilla Dissolution

• Episode 23

A bad day causes Penny to reevaluate her life choices – including Leonard. Meanwhile, Howard and Bernadette struggle to care for Mrs. Wolowitz, and Raj gets relationship advice from Sheldon.

The Status Quo Combustion

• Episode 24

Sheldon get upset about his career, the destruction of the comic book store and Leonard and Penny's future living arrangements. Howard and Bernadette can't keep hold of a carer for his mother.

The Locomotion Interruption

• Episode 1

Leonard and Amy take a road trip.

The Junior Professor Solution

• Episode 2

Howard takes a class that Sheldon's teaching.

The First Pitch Insufficiency

• Episode 3

Howard is invited by NASA to throw the first pitch at a game.

The Hook-Up Reverberation

• Episode 4

Penny wonders why Raj's girlfriend doesn't like her.

The Focus Attentuation

• Episode 5

The guys unsuccessfully try to invent "the next big thing".

The Expedition Approximation

• Episode 6

Sheldon and Raj venture underground in the name of science.

The Misinterpretation Agitation

• Episode 7

Penny's flirtatious sales techniques work a little too well.

The Prom Equivalency

• Episode 8

Love is in the air when the gang recreates a prom night.

The Septum Deviation

• Episode 9

Leonard's minor surgery leads to Sheldon's major reaction.

The Champagne Reflection

• Episode 10

Sheldon records the final instalment of "Fun with Flags".

The Clean Room Infiltration

• Episode 11

Amy forces Sheldon to celebrate a Victorian Christmas.

The Space Probe Disintegration

• Episode 12

The guys finally agree to do something the girls like.

The Anxiety Optimization

• Episode 13

Sheldon asks his friends to challenge him.

The Troll Manifestation

• Episode 14

Leonard and Sheldon defend themselves from an online bully.

The Comic Book Store Regeneration

• Episode 15

Everyone awaits the reopening of Stuart's comic bookstore.

The Intimacy Acceleration

• Episode 16

Sheldon and Penny try an experiment in falling in love.

The Colonization Application

• Episode 17
• PG 15-D
• 00:25:00

Sheldon applies for a one-way mission to colonise Mars.

The Leftover Thermalization

• Episode 18
• PG 15-D
• 00:25:00

A final family dinner is held for Mrs. Wolowitz.

The Skywalker Incursion

• Episode 19
• PG 15-D
• 00:25:00

Sheldon and Leonard try to sneak onto Skywalker Ranch.

The Fortification Implementation

• Episode 20
• PG 15-D
• 00:20:00

Wolowitz meets the half-brother he never knew he had.

The Communication Deterioration

• Episode 21
• PG 15-D
• 00:25:00

Penny contemplates a return to acting.

The Graduation Transmission

• Episode 22
• 00:25:00

Raj's father cuts him off from the family fortune.

The Maternal Combustion

• Episode 23
• PG 15-D
• 00:25:00

Sparks fly when Leonard and Sheldon's mothers finally meet.

The Commitment Determination

• Episode 24
• PG 15-D
• 00:25:00

Sheldon pushes Leonard and Penny to set a date.

The Matrimonial Momentum

• Episode 1
• PG 15-D
• 00:25:00

After driving to Vegas to get married, Penny struggles with Leonard’s confession that he kissed another girl. Also, Sheldon doesn't know how to act after Amy pushes pause on their relationship.

The Separation Oscillation

• Episode 2
• PG 15-D
• 00:25:00

Leonard confronts the woman he kissed on the North Sea in an attempt to set Penny's mind at ease. Also, Sheldon films a special episode of 'Fun with Flags' after his breakup with Amy

The Bachelor Party Corrosion

• Episode 3
• PG 15-D
• 00:25:00

The guys' science skills are put to the test when they get a flat tire during Leonard's bachelor party weekend in Mexico. Also, the girls force Penny to finally tell her family that she eloped with Leonard.

The 2003 Approximation

• Episode 4
• PG 15-D
• 00:25:00

Sheldon learns of an impending change in his living arrangements and decides to revert back to 2003, a simpler time before he met Leonard and Penny.

The Perspiration Implementation

• Episode 5
• PG 15-D
• 00:25:00

The guys take a fencing lesson from Barry Kripke and Sheldon finds himself in an awkward position when Kripke expresses interest in Amy.

The Helium Insufficiency

• Episode 6
• PG 15-D
• 00:25:00

In the midst of a nation-wide helium shortage, Sheldon and Leonard take desperate measures to get the supplies they need. Also, Penny and Bernadette download a dating app on Amy's phone to try and find her a new man.

The Spock Resonance

• Episode 7
• PG 15-D
• 00:25:00

Wil Wheaton interviews Sheldon for a Star Trek documentary where he reveals the ring and his plan to propose to Amy. Bernadette wants to start renovating the house and the topic of starting a family together with Howard is brought up.

The Mystery Date Observation

• Episode 8
• PG 15-D
• 00:25:00

Sheldon, Wolowitz and Koothrappali post an online advertisement to find Sheldon a new girlfriend. Also, when Amy is coy with details about a guy she is dating, Penny and Bernadette decide to spy.

The Platonic Permutation

• Episode 9
• PG 15-D
• 00:25:00

Sheldon and Amy try hanging out as friends when they spend Thanksgiving together at the aquarium. Also, Wolowitz reluctantly agrees to volunteer at the soup kitchen with Bernadette, Raj and Emily.

The Earworm Reverberation

• Episode 10
• PG 15-D
• 00:25:00

Sheldon has a revelation when he realizes why a song was stuck in his head. Also, Amy invites Dave over for dinner despite their previously awkward date.

The Opening Night Excitation

• Episode 11
• PG 15-D
• 00:25:00

After more than five years of dating, Sheldon and Amy spend their first night together. Also, Leonard, Wolowitz, and Koothrappali must decide who will take their extra Star Wars movie ticket.

The Sales Call Sublimation

• Episode 12
• PG 15-D
• 00:30:00

Penny gets more than she bargained for when Leonard agrees to meet with a psychiatrist on her behalf. Also, Sheldon and Koothrappali collaborate on an astronomical discovery.

The Empathy Optimization

• Episode 13
• PG 15-D
• 00:25:00

After having to deal with a sick Sheldon, Leonard, Penny and the gang try to treat themselves to a Sheldon-free weekend.

The Meemaw Materialization

• Episode 14
• PG 15-D
• 00:25:00

Meemaw meets Amy, but it isn't all roses. Meemaw seems to have an axe to grind with her. Sheldon comes to Amy's defense, but not before Meemaw lets a little secret of his slip.

The Valentino Submergence

• Episode 15
• PG 15-D
• 00:25:00

Sheldon and Amy host a live Valentine's Day episode of Fun with Flags, Leonard and Penny grapple with getting older, Howard and Bernadette find a surprise in their hot tub and Raj is torn between Emily and the cute girl he met at the Comic Bookstore.

The Positive Negative Reaction

• Episode 16
• PG 15-D
• 00:25:00

When the gang finds out about Bernadette’s pregnancy, they celebrate by singing karaoke.

The Celebration Experimentation

• Episode 17
• PG 15-D
• 00:25:00

After more than nine years together, the gang finally celebrates Sheldon’s birthday, surprising him with a special guest.

The Application Deterioration

• Episode 18
• PG 15-D
• 00:25:00

Leonard, Sheldon, and Wolowitz run into problems when they file for a patent for their infinite persistence gyroscope. Also, Penny, Amy and Bernadette give Koothrappali dating advice when Emily reaches out to him after their breakup.

The Solder Excursion Diversion

• Episode 19
• PG 15-D
• 00:25:00

Amy is shocked at a revelation from Sheldon after she buys him a new laptop. Also, Koothrappali sells out Leonard and Wolowitz after they lie to their wives in order to attend an early screening of a movie.

The Big Bear Precipitation

• Episode 20
• PG 15-D
• 00:25:00

Sheldon spills a secret of Leonard’s when the two take a weekend cabin trip with Penny and Amy. Also, when Koothrappali goes overboard with pregnancy gifts, Wolowitz and Bernadette must draw the line.

The Viewing Party Combustion

• Episode 21
• PG 15-D
• 00:25:00

Everyone must choose sides when a small argument between Leonard and Sheldon erupts into a heated fight during a group get-together.

The Fermentation Bifurcation

• Episode 22
• PG 15-D
• 00:30:00

The gang goes to a wine bar and runs into Penny’s old boyfriend, Zack. Also, Bernadette gets stuck spending the evening with Sheldon when she can’t go wine tasting with the group.

The Line Substitution Solution

• Episode 23
• PG 15-D
• 00:25:00

Sheldon hires Stuart to spend the day with Amy when he’d rather go to a movie screening. Also, Leonard’s mother, Beverly, comes to town and Penny struggles to make a connection with her.

The Convergence Convergence

• Episode 24
• PG 15-D
• 00:25:00

Chaos ensues when Leonard’s recently divorced parents, Alfred and Beverly, and Sheldon’s devoutly religious mother, Mary, come to town.

The Conjugal Conjecture

• Episode 1

After Sheldon's mother and Leonard's father share an evening together, everyone deals with an awkward "morning after the night before" in the tenth season premiere.

The Military Miniaturization

• Episode 2

Colonel Williams, an Air Force representative from the Department of Material Command, sits down for a talk with Howard.

The Dependence Transcendence

• Episode 3

Tensions rise when the guys struggle to complete their government project on time - and Sheldon tries an energy drink to stay awake. Meanwhile, Penny and Amy go to a geologist's "party".

The Cohabitation Experimentation

• Episode 4

When Amy's apartment floods, she proposes a "cohabitation experiment" with Sheldon. Meanwhile, Raj learns the gender of Howard and Bernadette's baby….before they do.

The Hot Tub Contamination

• Episode 5

Sheldon threatens to break off their relationship when Amy refuses to adhere to his "bathroom schedule", putting their cohabitation experiment in jeopardy.

The Fetal Kick Catalyst

• Episode 6

Penny learns there are fans of her performance in "Serial Ape-ist" when she and Leonard attend a Comic Con event; Amy hosts a brunch at Penny's apartment; and Wolowitz makes an impulsive purchase.

The Veracity Elasticity

• Episode 7

Amy lies about repairs being made to her apartment so she can continue living with Sheldon; Leonard lets Penny decorate Sheldon's old room.

The Brain Bowl Incubation

• Episode 8

After a successful experiment combining their genes, Sheldon is determined to procreate with Amy. Meanwhile, Raj is embarrassed with his new date's occupation.

The Geology Elevation

• Episode 9

Sheldon struggles to contain his jealousy when CalTech geologist Bert wins the MacArthur Genius Fellowship. Stephen Hawking returns for a guest appearance.

The Property Division Collision

• Episode 10

A battle ensues when Leonard and Sheldon argue over who will get custody of their shared belongings. Christopher Lloyd guest stars.

The Birthday Synchronicity

• Episode 11

While Sheldon and Amy celebrate Amy's birthday, Howard and Bernadette welcome their new Baby Wolowitz.

The Holiday Summation

• Episode 12

Sheldon and Amy visit Leonard and Penny for the first time since the holidays and share details about their terrible trip to Texas. Laurie Metcalf returns as Sheldon's mother.

The Romance Recalibration

• Episode 13

When Leonard and Penny fight, Sheldon plays the unlikely peacemaker. Meanwhile, Howard and Raj try to fix a squeaky floorboard in the baby's room

The Emotion Detection Automation

• Episode 14

While Raj gets dating advice from his ex-girlfriends, Sheldon gets help reading people's feelings when he beta tests an emotion-detection invention.

The Locomotion Reverberation

• Episode 15

Leonard and Howard try to distract Sheldon by giving him tickets to a historic railway, while Penny and Amy take Bernadette out for the night, leaving Raj and Stuart with the baby.

The Allowance Evaporation

• Episode 16

Amy is furious when she learns Sheldon has shared intimate details of their relationship with people at the university, prompting their first fight since moving in together.

The Comic-Con Conundrum

• Episode 17

When Raj is cut off from his father's fortune, he appoints Sheldon in charge of his finances to help him get out of debt. Meanwhile, Penny considers joining Leonard at Comic-Con.

The Escape Hatch Identification

• Episode 18

When Raj moves out of his apartment, Leonard and Penny offer him Sheldon's old room. Christine Baranski returns as Leonard's mother, Beverly.

The Big Bang Theory

• Episode 18

The Collaboration Fluctuation

• Episode 19

Leonard, Penny and Raj adjust to their new living arrangement, while Sheldon takes an interest in Amy's work.

The Recollection Dissipation

• Episode 20

Sheldon pushes himself to the limit when he collaborates on projects with Leonard and Howard as well as Amy on the same day. Meanwhile, Bernadette nears the end of her maternity leave.

The Separation Agitation

• Episode 21

Howard and Bernadette have a hard time leaving Halley in daycare when Bernadette returns to work. Meanwhile, Bert introduces the gang to his new girlfriend, Rebecca.

The Cognition Regeneration

• Episode 22

Leonard isn't thrilled when Penny considers taking a new job offered by her ex-boyfriend, Zack.

The Gyroscopic Collapse

• Episode 23

After Leonard, Sheldon and Howard celebrate the completion of their top secret Air Force project, they're met with an unpleasant surprise.

The Long Distance Dissonance

• Episode 24

On the tenth season finale, the gang is concerned when Sheldon's former admirer, Dr. Ramona Nowitzki resurfaces while Amy is away at Princeton.