Rules of Engagement is a comedy about the different phases of male/female relationships, as seen through the eyes of a newly engaged couple, Adam and Jennifer, a long-time married pair, Jeff and Audrey, and a single guy on the prowl, Russell. As they find out, the often confusing stages of a relationship can seem like being on a roller coaster. People can describe the ride to you, but to really know what it's like you have to experience it for yourself.
Liz temporarily moves in with Jeff and Audrey, and quickly irritates Audrey when she takes Jeff's side on everything. Meanwhile, Adam and Timmy team up to beat the rest of the company at ping pong.
Jeff and Audrey ask Russell to list the women he has slept with so they can avoid giving one of those names to their baby. Meanwhile, Adam is humiliated when he spends a lot of money on a new bicycle and gear.
Liz wants to have a baby, so she turns to Russell for help. Meanwhile, Timmy takes Jeff's advice on how to attract a coworker, but it all backfires.
Jeff makes an effort to change his unhealthy eating habits after he accidentally eats Jen and Adam’s “special” cupcake and lands in the hospital. Meanwhile, Russell forces Timmy to be his wingman when his date brings her mother on their night out.
After meeting up with college friends who are no longer into partying, Jeff and Audrey set out to prove that even with a baby on the way, they can still have fun. Meanwhile, Timmy tricks Russell into accompanying him to a nursing home.
When Audrey bonds with their unborn baby, a paranoid Jeff believes she is trying to form an alliance against him. Meanwhile, Russell plagiarizes a real estate article that Timmy wrote.
Jeff plots to get into a popular restaurant that he promised to take Audrey to, after he fails to make a reservation.
Brenda gets Jeff and Audrey to help cater an event at Columbia University. Audrey tries to impress the attendees, but it's Jeff's bartending skills that wow the crowd. Meanwhile, Russell enthusiastically embraces Timmy's Bollywood culture.
Jeff and Audrey join Adam and Jen's healthy cooking class, but it turns into a competition after Jen insults Audrey's cooking. Meanwhile, Timmy is freaked out by his resemblance to Russell's new girlfriend, Radha.
When Jen discovers that the guys are not planning a surprise bachelor party for Adam as he expects, she forces them to do one for him. Meanwhile, Jen paints a mural for Audrey and Jeff’s nursery that turns out to be rather graphic.
Jeff tries to prove to Audrey that Heidi, a college friend, never had feelings for him; his plan goes awry, however, when she hits on him during a visit. Meanwhile, Timmy quits when he discovers Russell has embedded a pet tracking device in him.
Jeff is determined to make Brenda laugh when he discovers that she has a “wee” problem due to her pregnancy. Meanwhile, Timmy is surprised by the professionalism of his new boss while Russell is frustrated with his new assistant.
Brenda goes into labor on Jennifer and Adam's wedding day. Meanwhile, Russell and Timmy make an attempt at reconciliation and Audrey surprises Jeff.