When Grace receives an unexpected marriage proposal from her boyfriend, Will tries to be supportive of her decision but finally tells her that she's making a mistake, even though he's putting their friendship at risk. The situation is complicated by interference from Grace's socialite assistant, Karen, and Will's outrageous friend, Jack.
Will must decide whether to support Grace's independence by encouraging her to take an apartment across town or selfishly keep her close by inviting her to share his living space. The decision may be made easier, however, by the nagging presence of Will's current roommate, Jack, and his parrot, Guapo. Meanwhile, Karen and Jack meet for the first time and find each other to be fabulous.
When Grace moves in with Will, she complains that the guest bathroom is too small and suggests knocking the common wall down to create one big master bathroom, which results in Will having to confront his own issues on change and his ability to have a successful relationship. Meanwhile, Jack and Karen bear the brunt of Will and Grace's displaced anger.
When Grace decorates Harlin's apartment, she gets carried away with a cowboy theme. Will is both shocked and embarrassed by the cowboy chic and makes an even greater mess of the situation. Meanwhile, Jack decides to embark on a “singing career“ with a little help from Karen.
Will and Grace plan to spend a serious Halloween together watching Ingmar Bergman movies at home--until Harlin drops off his over-eager kids at their place when he's called away on business. Meanwhile, Jack convinces Karen to accompany him to the downtown parade where she becomes an honorary drag queen.
When Jack reveals to Grace that Will once had an affair with a "client," she becomes paranoid that Will is keeping secrets from her. Her suspicions continue to grow when Will meets Karen for a discreet meeting to discuss her legal problems and will only tell Grace he's meeting with a client.
Grace blames her relationship with Will as the reason for her lack of interest in dating and decides they can no longer have fun together. Meanwhile, Jack enlists Will's help when the IRS catches up with him.
Grace has the opportunity to buy the studio that serves as her office space and turns to Will for first-time buyer advice. However, Will's negotiating tactics lead Grace to believe that Will thinks she is incapable of closing the deal and she sets out to prove him wrong. Meanwhile, Jack wants to become a massage therapist and practices his technique on a delighted Karen.
After Grace defies Will's wishes and brings home a puppy, Will can't resist the pooch and begins to treat him like a newborn baby. Meanwhile, Jack and Karen worry about the dog's effect on Will and Grace and insist that the new parents go out for a night on the town.
Will and Grace become hooked on a real-life soap opera unfolding in their neighbors' apartment when they begin eavesdropping through the new heating vent in their floor. As Will and Grace live vicariously through the marital infidelities of the downstairs couple, Jack feels neglected and enlists Karen's help in staging a play that drives the message home to his two best friends.
It's Will's birthday and all he wants is a nice, quiet dinner with his two best friends, Grace and Jack. When Jack and Grace discover they share a passion for figure skating, they surprise Will with tickets for Champions on Ice and Karen reluctantly joins the special evening.
Will hires a cleaning lady to ""rescue"" his designing roommate Grace from the creative chaos that litters their apartment, and while preparing for an annual decorators' contest, Grace develops a dependency on her maid and can't create without her. Meanwhile, Jack poses as an attorney in Will's office to impress an attractive guy he hopes to date.
Grace's visiting mom, Bobbi Adler, a would-be star whose propensity for breaking out into show tunes and impressions dismays her daughter â€“ and delights Will, Jack and Karen â€“ wreaks havoc by suggesting Will and Grace wed, despite their sexual differences. When Will winces at the fantasy of committing to anyone who needs to be the star of a relationship, Grace realizes she's more of a chip off the old block than she imagined.
A ""surprise"" birthday party for Jack astounds Will when his estranged older brother Sam turns up at the fete at Grace's invitation. Not only do sparks fly between the brothers, but electricity of a different sort crackles between Grace and Sam. Meanwhile, Karen flashes her platinum card for Jack as the pair shop until they drop at a boutique where the snooty salesmen previously had snubbed Jack.
A wary Grace tells Will of her romance with his brother, Sam, and unleashes an avalanche of resentment. While Will wrestles with sibling rivalry, Karen helps Jack come to grips with turning 30 by hiring him as her personal assistant and leads Grace to sort through her true feelings for the Trumans.
Stunned to find they have a 'date' with the same guy, Will and Grace compete for the affections of a handsome, charming new neighbor at dinner, and even Jack's finely-tuned gaydar can't pick up his preference. Meanwhile, Karen contemplates firing her driver and in a twist of irony asks Grace to role-play firing an incompetent employee.
The gang retreats to a cabin in Vermont for the weekend, where Grace rekindles romance with an old flame and tries to hide the fling from Will, who's pining on the eve of his would-be anniversary. Meanwhile, Karen's culinary efforts go up in smoke, as does Jack's attempt to cheer Will by dragging him to a gay pub, where the town barber-turned-hair stylist sidles up to him.
Will finds a "substitute Grace" in Val, a new neighbor who is available for plans with Will while Grace is consumed with work. As Will and Val continue to spend more time together, Grace fears that she has been replaced and fights with Val to regain Will's attention. Meanwhile, Jack seeks support from Karen after the court finds him guilty of slapping a meter maid and sentences him to pick up trash.
Will invites Jack to his gym on a "buddy pass," but when he expresses his embarrassment to Grace over his buddy's gay behavior, Jack overhears the comments and looks to set him straight about prejudice. Meanwhile, Grace continues to lend her ear when Karen's marriage hits rocky ground and she and Karen share an evening of girl talk.
A successful and arrogant New York publicist hires Grace to decorate his house with the condition that she fixes him up with Will. But there's a problem: Will can't stand the guy. Meanwhile, Jack uses Karen to teach Will how to kiss someone he finds unattractive.
When Rob and Ellen admit that they don't have fun playing games with Will and Grace because of Grace's competitive nature, Grace works to change her image. However, as Grace loses her competitive edge, Will's emerges and he convinces his partner to care only about winning. Meanwhile, after learning how to administer CPR from Jack, Karen saves a workman's life.
Will is stunned to discover that Grace is dating her ex-fiance Danny once again, but he chooses not to interfere after he's accused of being meddlesome. Meanwhile, Jack agrees to take a walk down the aisle with Karen's combative maid, Rosario, who needs a groom to help her smooth out some immigration problems.