Stunt casting stumbles (Jean-Claude Van Damme, Charlie Sheen) aside, the second season was a very good year. Ross and Rachel were the engine that drove the season and produced some of the series' most monumental episodes, including "The One with Ross' New Girlfriend," "The One Where Ross Finds Out" (with R & R's first kiss), "The One with the List," "The One with the Prom Video," and "The One Where Ross and Rachel... You Know." But this was not the only significant story arc. Enter--and, in the bittersweet season finale, exit--Tom Selleck as Dr. Richard Burke, the family friend ("He's like a brother to... Dad," notes a disapproving Ross) who becomes Monica's (Courtney Cox) lover. Joey (Matt LeBlanc) finds success (albeit short-lived) as Dr. Drake Ramoray on "Days of Our Lives" and moves out ("We're not Bert and Ernie," he tells roommate Chandler). Future Emmy winner Lisa Kudrow's best season is to come, but, as Phoebe, she makes the most of some memorable subplots, including! her shocked discovery of sad movie endings she had been shielded from ("The One Where Old Yeller Dies"), her dispute with Ross over evolution ("The One Where Heckles Dies"), and her channeling of an elderly woman who died on her massage table ("The One with the Lesbian Wedding").

Friends' peerless writing staff really spread the wealth in the pivotal third season. Each of this seamless ensemble's cast members was given a story arc that deepened and enriched their characters. Most devastatingly, Ross and Rachel's romance is torn asunder by Ross's jealousy (not to mention his one-night stand while the couple are, now famously, "on a break"). Phoebe is reunited with her half brother (Giovanni Ribisi) and meets a family friend (Terri Garr; inspired casting) who drops a Darth Vader-esque bombshell about Phoebe's parentage. Monica begins the season reeling from her breakup with Richard, but rebounds with millionaire Pete (Jon Favreau from Swingers). Chandler is driven to increasingly hysterical attempts to "go through the tunnel" and commit to his relationship with Janice (Maggie Wheeler). And womanizer Joey reveals his soulful side when he falls for an initially contemptuous theatrical costar. Also lending memorable support are Alison LaPlac! a, as Rachel's self-absorbed new boss, and an Emmy-worthy Ben Stiller ("The One with the Screamer") as Rachel's new boyfriend whose volcanic temper only erupts in front of Ross. Among the A-list cameos, Robin Williams and Billy Crystal ("The One with the Ultimate Fighting Champion") are woeful, but more memorable is Isabella Rossellini ("The One with Frank Jr."), whom the hapless Ross meets just after crossing her off his "freebie list" of celebrities Rachel would allow him to sleep with. Other classic episodes include the season-opener, "The One with the Princess Leia Fantasy" and "The One with the Flashback," which offers some provocative near-couplings between Monica and Joey, Ross and Phoebe, and Chandler and Rachel. Add a chick and a duck ("The One with a Chick, and a Duck"), and you have a benchmark season in this irreplaceable series.

Friends' fourth season, one of the very best and most consistently satisfying, begins with Chandler urinating on Monica's leg to relieve a jellyfish sting. It ends with the two in bed and in lust. In between are several benchmark episodes and rich, character-enriching plot developments that keep this series from coasting on comfort level. Phoebe agrees to become a surrogate mother for her long-lost brother. Chandler "crosses the line" after falling in love with Joey's girlfriend, and is forced to spend one memorable Thanksgiving in a box. Rachel desperately pursues the recently divorced Joshua (then real-life squeeze Tate Donovan). Joey and Chandler trade spaces with Monica and Rachel, and then, with provocative (albeit offscreen) sapphic compensation, return to their humble abode. And Ross meets the warm and wonderful Emily (Helen Baxendale), setting the stage for a London wedding and classic season finale that revitalizes our rooting interest in the whole Ross and R! achel thing. Especially jolly good in this two-parter are the scene-stealing British character actors, including Hugh Laurie as the unfortunate airline passenger seated next to Rachel as she wings toward London to tell Ross she loves him ("And by the way, it seems to be perfectly clear that you were on a break," he tries to reason with her), and Tom Conti and an absolutely fabulous Jennifer Saunders as Emily's squabbling parents. --Donald Liebenson

Divorce number 2 is immediately on the cards as the fifth season opens with "The One After Ross Says Rachel." As of this point, Ross's character undergoes some extreme personality changes (which apparently lost David Schwimmer many female fans). His incessant whining drives all the Friends to distraction, especially in "The One Where Ross Moves In" with Chandler (Matthew Perry) and Joey (Matt LeBlanc). Later things get uncomfortable both at work and at home when he goes through a period of rage ("The One with Ross's Sandwich"). While all this downplays his failed relationship with Rachel (Jennifer Aniston), the real idea is to allow focus on the secret pairing of Chandler and Monica (Courteney Cox) after a night of passion in London. This made for a return to the show's appealingly silly atmosphere as poor Joey is caught in the middle of everyone's secrets. Building to "The One Where Everybody Finds Out," the silliness pauses for some genuinely touching interplay between Perry and Cox. The previous year's semi-serious thread about Phoebe's (Lisa Kudrow) birth gets forgotten fast: to distract the viewer she's introduced to Gary (Michael Rapaport) in "The One with the Cop." This leads to some hilarious parodying with Phoebe interrogated about apartment hunting, and the guys excited and then scared in "The One with the Ride-Along." She's more than over him by the time of the two-part finale, "The One in Vegas," though, especially since she missed out on London. Just in case fans thought Chandler and Monica had permanently stolen the spotlight, a cliffhanger shocks expectation again with Ross and Rachel bursting out of a chapel.... --Paul Tonks