Leonard and Penny's relationship takes a turn for the worse when they break up, but is quickly resolved. Soon their relationship progresses into a stronger friendship than before, while Sheldon and Penny's friendship slowly begins.
S02E01 The Bad Fish Paradigm
Sep 22, 2008After her first date with Leonard goes awry, Penny finds an unwilling confidant in Leonard's anti-social roommate, Sheldon.
30m
S02E02 The Codpiece Topology
Sep 29, 2008When Leonard sees Penny with a handsome new guy, he enters into a rebound relationship with Sheldon's nemesis, Leslie Winkle.
30m
S02E03 The Barbarian Sublimation
Oct 6, 2008Sheldon creates a monster when he introduces Penny to the world of online gaming.
30m
S02E04 The Griffin Equivalency
Oct 13, 2008Raj, newly famous because of an article in a magazine, gets a big head and makes a disastrous play for Leonard's crush, Penny.
30m
S02E05 The Euclid Alternative
Oct 20, 2008Leonard and his friends stage an intervention to make Sheldon confront his longstanding refusal to drive.
30m
S02E06 The Cooper-Nowitzki Theorem
Nov 3, 2008Young grad student's attraction to Sheldon confuses everyone, including Sheldon himself.
30m
S02E07 The Panty Piñata Polarization
Nov 10, 2008Penny vows to get revenge on Sheldon when he bans her from the apartment for a series of petty infractions.
30m
S02E08 The Lizard-Spock Expansion
Nov 17, 2008Wolowitz thinks he's found the love of his life, until she meets Leonard.
30m
S02E09 The White Asparagus Triangulation
Nov 24, 2008Sheldon can barely contain his joy when Leonard starts dating a woman who meets Sheldon's exacting standards.
30m
S02E10 The Vartabedian Conundrum
Dec 8, 2008Sheldon uses Dr. Stephanie to check all his hypochondriac symptoms. When Leonard's relationship with a new woman starts moving too fast for him, he goes to Penny for advice.
30m
S02E11 The Bath Item Gift Hypothesis
Dec 15, 2008Christmas is a source of stress for Leonard - whose handsome colleague starts dating Penny - and his friends, who are being tormented by Sheldon's obsession with gift-giving etiquette.
30m
S02E12 The Killer Robot Instability
Jan 12, 2009When Penny's comment about Wolowitz's love life sends him into a depressed stupor, his friends lose their most important team-mate in an upcoming fighting robot competition.
30m
S02E13 The Friendship Algorithm
Jan 19, 2009Socially awkward Sheldon develops a scientific procedure for making friends.
30m
S02E14 The Financial Permeability
Feb 2, 2009Sheldon's "simple" solution to Penny's financial problem leads to a confrontation between Leonard and Penny's hulking ex-boyfriend, Kurt.
30m
S02E15 The Maternal Capacitance
Feb 9, 2009Disastrous visit from Mrs. Hofstadter brings Leonard and Penny closer together.
30m
S02E16 The Cushion Saturation
Mar 2, 2009Paintball game leads to a fight between Penny and Sheldon, and romance for Wolowitz and Leslie.
30m
S02E17 The Terminator Decoupling
Mar 9, 2009Train trip to San Francisco takes a major detour when Sheldon discovers he forgot his flash drive and Leonard, Wolowitz and Raj discover that sci-fi actor Summer Glau is onboard.
30m
S02E18 The Work Song Nanocluster
Mar 16, 2009Penny's home hair products business becomes a complete nightmare when a caffeine-addled Sheldon takes over.
30m
S02E19 The Dead Hooker Juxtaposition
Mar 30, 2009Penny develops a rivalry with a sexy female neighbor who threatens to become "The New Penny" in the building.
30m
S02E20 The Hofstadter Isotope
Apr 13, 2009While a fellow comic book-loving pal of the guys romances Penny, Leonard and Wolowitz venture out into the world of "Ladies' Night" at a local bar.
30m
S02E21 The Vegas Renormalization
Apr 27, 2009Leonard and Koothrappali take a heartbroken Wolowitz to Las Vegas, leaving Sheldon locked out of his apartment and forced to bunk with Penny.
30m
S02E22 The Classified Materials Turbulence
May 4, 2009Things begin to look up for Leonard when Penny makes a surprising revelation on her second date with Stuart. Meanwhile, Wolowitz enlists his friends' help when he discovers a critical design flaw in his project for NASA.
30m
S02E23 The Monopolar Expedition
May 11, 2009Penny is conflicted when Leonard and his friends decide to spend the summer working - at the North Pole.
30m
