McCormick was born and raised in Midland, Texas, and graduated first in her class from The Kinkaid School in Houston in 1977. She graduated with honors from Williams College in 1981 with a B.F.A. She also holds an M.F.A. from the American Conservatory Theater in San Francisco. She has worked in television, movies, theatre, and voice acting. Her breakthrough role was Enemy Mine directed by Wolfgang Petersen with Dennis Quaid. Her other film credits include Woody Allen's Whatever Works, You Know My Name with Sam Elliott, and A Simple Twist of Fate with Steve Martin. Her first notable television credit was district attorney Rita Fiore in ', a role she played from 1986 to 1987. She appeared as the holodeck simulation Minuet in "11001001", a first-season episode of ', and later as Minuet Riker in a fantasy-alternate universe during the fourth-season episode "Future Imperfect". The role she would become best known for was on NBC network as Dr. Elizabeth Olivet on Law & Order, appearing in approximately half of the series episodes between 1994 and 2006. In 1997, she played the unhappy wife of a police psychiatrist played by Robert Pastorelli in the short-lived Americanized version of the British series Cracker. She has been a guest star on series including Madam Secretary, Elementary, Blue Bloods, Judging Amy, The Practice, Body of Proof, Cold Case, , and LA Law. She also performs on stage. She appeared at the Off-BroadwayCherry Lane Theatre in Eve-olution with The Cosby Show star Sabrina Le Beauf in 2004. She has also appeared in Dinner with Friends, Oedipus, Ancestral Voices, The Donahue Sisters, Laureen's Whereabouts and In Perpetuity. She worked with Thomas Kail at The Flea Theatre in A. R. Gurney's Family Furniture. In 2015 she appeared in Vanya, Sonya, Masha and Spike at the PaperMill Playhouse and What I Did Last Summer at the Signature 2015. She appeared in the Broadway productions of The Dinner Partyin 2001 as Mariette Levieux, Private Lives in 2002, and in Equus in 2008 as Dora Strang. In 2012 she appeared opposite her husband, Byron Jennings, in the Off-Broadway production of Ten Chimneys. She appeared Off-Broadway in Will Eno's play The Open House in 2014. She has recorded many audio books, including the Hunger Games series, and has narrated many Ken Burns documentaries.
