Featured roles in 1998's "The Alarmist", as Stanley Tucci's scheming assistant, and "Deep Impact", as a pilot, followed, and a busy filming schedule led to her near ubiquity on movie screens in 1999. She was an infertile woman married to a religious fanatic in "Getting to Know You" (which debuted at Sundance) before playing a DEA agent in "Harvest", a drama about farmers growing marijuana to financially preserve their land. McCormack was also featured as a romantic partner for director-star Clint Eastwood in the thriller "True Crime" and portrayed the wife of a small-time hockey player (Russell Crowe) who ends up in a game versus the New York Rangers in "Mystery, Alaska" (1999), a film produced and penned by David E Kelley. Additional projects featuring the actress included "The Big Tease", a comedy co-starring Frances Fisher and Craig Ferguson (who also scripted) about a small town Scottish hairdresser who enters the hairdressing world championships in Los Angeles; a supporting turn in "The Broken Hearts Club: A Romantic Comedy"; and "Gun Shy" (all 2000), a Eric Blakeney action comedy film starring Liam Neeson and Sandra Bullock which bombed out of the gate. She also starred with Minnie Driver in the woefull crime comedy "High Heels and Low Lifes" (2001) as one of a pair of downtrodden regular gals caught up in a blackmail scheme, but the actress fared better in the ensemble of writer-director Bart Freundlich's film "World Traveler" (2001). She also had a fine but underutilized turn as Jeff Bridges' wife in the dramedy "K-PAX" (2001). McCormack was particularly excellent as the depressed, lovelorn masseuse in "Full Frontal" (2002), director Steven Soderbergh's arty,low-tech and chilly meditation on Los Angelenos. She next appeared as the adoptive mother of David Spade's full-grown ex-kiddie actor in "Dickie Roberts: Former Child Star" (2003).

In addition to her numerous film appearances, in 1999 theatergoers saw McCormack return to the stage in a high-profile role utilizing her capable singing voice. She succeeded luminaries Natasha Richardson and Jennifer Jason Leigh as Sally Bowles in the popular Broadway revival of "Cabaret". A versatile performer, McCormack is convincing playing anything from a fresh-faced siren to a hard-nosed law enforcer. She returned to the stage, this time in London, as one of the stars of Neil LaBute's "bash, latter day plays", a collection of one-act plays.