This season follows Ross and Rachel living together with baby Emma after she and Joey clear up the misdirected proposal. Rachel soon moves back in with Joey after a fight with Ross, discovering that she has feelings for Joey.
Aisha Tyler portrays Charlie Wheeler, a paleontologist that Ross meets and becomes attracted to. When Ross and Rachel decide to kiss their love interests, they find both Joey and Charlie kissing at Joey's rooftop party.
Monica and Chandler, inspired by Ross and Rachel, decide to conceive a child of their own. They seek medical advice after several episodes of trying for a baby. Upon discovering that it is unlikely that they will be able to conceive through natural means, they decide to adopt a child.
Paul Rudd appears in the recurring role of Mike Hannigan, a new boyfriend for Phoebe. When Mike tells Phoebe that he never wants to marry again, Hank Azaria returns as David "the scientist guy," a character originated in the first season. Phoebe becomes conflicted when both men propose to her. She chooses Mike over David, but decides not to marry him.
The finale is set in Barbados, where the group goes to hear Ross give a keynote speech at a paleontology conference.
Not only do Charlie and Joey find out they have nothing in common, but Charlie also finds herself eventually becoming attracted to Ross. After Charlie dumps Joey, Joey and Rachel's feelings for each other return. They agree to clear it with Ross first, until Joey catches Ross kissing Charlie. The finale ends with Joey and Rachel kissing.