McKerrow was born in Albuquerque, New Mexico, and began her ballet training at the age of seven at the Twinbrook School of Ballet in Rockville, Maryland. She later studied with Mary Day at the Washington School of Ballet, where she danced with the company for two years and toured extensively throughout the United States and Europe.
MeKerrow joined American Ballet Theatre under the direction of Mikhail Baryshnikov in 1982, was appointed a soloist in 1983, and became a principal dancer in 1987. Her repertoire included: the leading roles in Cinderella, Giselle, Romeo and Juliet, Manon, La Bayadère, Coppélia, Don Quixote, The Sleeping Beauty, Swan Lake, La Sylphide and The Nutcracker. She has been acclaimed for performances of shorter works by George Balanchine, Antony Tudor, Sir Frederick Ashton, Jerome Robbins and Jiří Kylián. McKerrow has created roles in ballets by choreographers such as Twyla Tharp, Clark Tippet, James Kudelka, Agnes de Mille, Choo San Goh and Mark Morris. She has also appeared as a guest artist with ballet companies throughout the world.
In 2000, together with her husband John Gardner, McKerrow began working
for the Antony Tudor Trust, staging and coaching his superlative ballet,
The Leaves Are Fading, around the country. She has also staged
numerous other ballets for professional companies and schools across
the United States. During her last ten years performing as a principal
ballerina with American Ballet Theatre, she spent as much time as she
could working with students and young dancers. Upon her retirement from
ABT in 2005, she has devoted the majority of her time to teaching and
coaching this great art form.