Fields was born and raised in Chicago, Illinois. He started as a self-taught rock musician but soon was influenced by the musicians of the Association for the Advancement for Creative Musicians, which was active in the Hyde Park neighborhood in which he grew up. Later he studied classical guitar, jazz guitar, music composition and music theory. In 1970 Fields co-founded the power avant-jazz trio Life Rhythms. When the group disbanded two years later he played sporadically, but soon all but quit music until 1989.
Since then he has performed and composed actively. His ensembles and partnerships have included such musicians as Marilyn Crispell, Hamid Drake, John Hollenbeck, Joseph Jarman, Myra Melford, Jeff Parker, and Elliott Sharp