[4] Parker was not formally trained as a classical player, but in his youth studied with Jimmy Garrison, Richard Davis, and Wilbur Ware in learning the tradition.

[8][9] Parker's "breakout" albums were released in the early 2000s, first with the William Parker Quartet (with saxophonist Rob Brown, drummer Hamid Drake, and trumpeter Lewis Barnes): O'Neal's Porch was included in Best of 2001 lists in The New York Times,[10] DownBeat,[3] and the Jazz Journalists Association;[11] in 2002, Raining on the Moon, featuring guest Leena Conquest, received rave reviews in publications including Pitchfork.

Petit Oiseau was chosen as one of the best jazz disks of 2008 by The Wall Street Journal,[13] the BBC's Radio Three,[14] The Village Voice,[15] and PopMatters.

In June 2011, Parker's second book, Conversations, a collection of interviews with notable free jazz musicians and forward thinkers, mainly from the African-American community, was published by RogueArt.

[23] With Fred Anderson With Billy Bang With Albert Beger With John Blum (pianist) With Peter Brötzmann With Peter Brötzmann Chicago Tentet With the Brötzmann Clarinet Project With Brötzmann's Die Like A Dog Quartet With Rob Brown With Roy Campbell, Joe McPhee & Warren Smith With Daniel Carter and Federico Ughi With Bill Dixon With Hamid Drake and Bindu With Marco Eneidi With Charles Gayle With Frode Gjerstad With Alan Glover With Wayne Horvitz With Gianni Lenoci With Frank Lowe With Jimmy Lyons With Raphe Malik With Michael Marcus With Thollem McDonas & Nels Cline With the Melodic Art-Tet (Charles Brackeen, Ahmed Abdullah, Parker, Roger Blank, Tony Waters) With Roscoe Mitchell With Jemeel Moondoc With Joe Morris With Other Dimensions In Music With Ivo Perelman With Hugh Ragin With Matthew Shipp With Steve Swell With Cecil Taylor With David S Ware