Schuman was born into a Jewish family in Manhattan, New York City, son of Samuel and Rachel Schuman. He was named after the 27th U.S. president, William Howard Taft, though his family preferred to call him Bill. Schuman played the violin and banjo as a child, but his overwhelming passion was baseball. He attended Temple Shaaray Tefila as a child. While still in high school, he formed a dance band, "Billy Schuman and his Alamo Society Orchestra", that played local weddings and bar mitzvahs in which Schuman played string bass.
In 1928 he entered New York University's School of Commerce to pursue a business degree, at the same time working for an advertising agency. He also wrote popular songs with E. B. Marks Jr, a friend he had met long before at summer camp. Around that time, Schuman met lyricist Frank Loesser and wrote some forty songs with him. Loesser's first published song, "In Love with a Memory of You", credits the music to William H. Schuman.
On April 13, 1930, Schuman went with his older sister, Audrey, to a Carnegie Hall concert of the New York Philharmonic, conducted by Arturo Toscanini. According to the Philharmonic's archives, the program included works by Brahms, Mendelssohn, Castelnuovo-Tedesco and Smetana. Of this experience, Schuman later said, "I was astounded at seeing the sea of stringed instruments, and everybody bowing together. The visual thing alone was astonishing. But the sound! I was overwhelmed. I had never heard anything like it. The very next day, I decided to become a composer."[this quote needs a citation]
Schuman dropped out of school and quit his part-time job to study music at the Malkin Conservatory with Max Persin and Charles Haubiel. From 1933 to 1938, he studied privately with Roy Harris. In 1935, he received a B.S. degree in music education from Teachers College at Columbia University. Harris brought Schuman to the attention of the conductor Serge Koussevitzky, who championed many of his works and conducted Schuman's Symphony No. 2 in 1939. Possibly Schuman's best known symphony, the Symphony for Strings, was commissioned by the Koussevitzky Foundation, dedicated to the memory of Natalie Koussevitzky, and was first performed under Koussevitzky on November 12, 1943.
Schuman won the inaugural Pulitzer Prize for Music in 1943 for his Cantata No. 2. A Free Song, adapted from poems by Walt Whitman. From 1935 to 1945, he taught composition at Sarah Lawrence College. In 1945, he became president of the Juilliard School, founding the Juilliard String Quartet while there. He left in 1961 to become the first president of Lincoln Center, a position he held until 1969. He won a special Pulitzer Prize in 1985 citing "more than half a century of contribution to American music as composer and educational leader" and he received the National Medal of Arts in 1987.
He died in New York City at age 81.
Schuman left a substantial body of work. His "eight symphonies, numbered Three through Ten", as he himself put it (the first two were withdrawn), continue to grow in stature. His concerto for violin (1947, rev. 1959) has been hailed as among his "most powerful works ... it could almost be considered a symphony for violin and orchestra." Other works include the New England Triptych (1956, based on melodies by William Billings), the American Festival Overture (1939), the ballets Undertow (1945) and Judith (1949) (the latter written for Martha Graham), the Mail Order Madrigals (1972) to texts from the 1897 Sears Roebuck catalog, and two operas, The Mighty Casey (1953, based on Ernest Thayer's "Casey at the Bat"), which reflected his lifelong love of baseball, and A Question of Taste (1989, after a short story by Roald Dahl). He also arranged Charles Ives' organ piece Variations on "America" for orchestra in 1963, in which version it is better known. Another popular work by William Schuman is his George Washington Bridge (1950), for concert band.
William Schuman appeared as the opening guest on the CBS game show, What's My Line? on September 30, 1962 (episode No. 632). Because of his recognizability, panel members Dorothy Kilgallen, Martin Gabel, Arlene Francis and Bennett Cerf were blindfolded. Schuman's title card identified him as "Composer and President of Lincoln Center for the Performing Arts (New York City)". Schuman displayed his wit in response to panel questions. After the panel exhausted a few categories, Kilgallen asked, "What about music?" Schuman replied, "What about it?" When asked if he was Leonard Bernstein, Schuman replied, "He's a friend." When asked if he was Rudolf Bing, Schuman repeated, "He's a friend", prompting Francis to wonder who was not his friend. When asked if he had ever sung for the Metropolitan Opera, Schuman said, "Often desired to, never invited." Cerf identified him after host John Charles Daly had flipped over all the cards. Daly announced that Schuman's Eighth Symphony would be performed at Philharmonic Hall (now Avery Fisher Hall) the following Thursday, which date, October 4, 1962, marked the première of the work. It was recorded for Columbia Masterworks Records five days later by its performers, the New York Philharmonic conducted by Bernstein.
- The Mighty Casey (1953, based on Ernest Thayer's "Casey at the Bat")
- A Question of Taste (1989, after a short story by Roald Dahl)
- Undertow (1945, written for Antony Tudor)
- Night Journey (1947, written for Martha Graham)
- Judith (1949, written for Martha Graham)
- Voyage for a Theatre (1953, written for Martha Graham; withdrawn)
- The Witch of Endor (1965, written for Martha Graham; withdrawn)
- Symphony No. 1 (1935; withdrawn)
- Symphony No. 2 (1937; withdrawn)
- Symphony No. 3 (1941)
- Symphony No. 4 (1941)
- Symphony for Strings (Symphony No. 5) (1943)
- Symphony No. 6 (1948)
- Symphony No. 7 (1960)
- Symphony No. 8 (1962)
- Symphony No. 9 Le fosse Ardeatine (1968) [viz. Ardeatine massacre]
- Symphony No. 10 American Muse (1976)
- American Festival Overture (1939)
- Prayer in Time of War, originally titled Prayer 1943 (1943)
- Circus Overture (1944)
- Credendum (1955, commissioned by UNESCO)
- New England Triptych (1956, based on melodies by William Billings)
- In Praise of Shahn (1969)
- American Hymn (1980)
- Showcase: A Short Display for Orchestra (1986)
- Piano Concerto (1938; published but withdrawn)
- Piano Concerto (1942; third movement contains material from 1938 concerto)
- Violin Concerto (1947; 1st rev., 1954; 2nd rev. 1957–8)
- A Song of Orpheus, for cello and orchestra (1962)
- To Thee Old Cause, for oboe and orchestra (1968)
- Concerto on Old English Rounds, for viola, female chorus and orchestra (1973)
- Three Colloquies, for horn and orchestra (1979)
- Prelude for Voices (1939, to texts by Thomas Wolfe)
- Orpheus with His Lute (1944, to a text by William Shakespeare)
- Five Rounds on Famous Words (1956/69)
- Carols of Death (1958, to texts by Walt Whitman)
- Mail Order Madrigals (1972, to texts from the 1897 Sears Roebuck catalog)
- The Young Dead Soldiers (1975, to a text by Archibald MacLeish)
- Time to the Old (1980, to texts by Archibald MacLeish)
- Perceptions (1982, to texts by Walt Whitman)
- Esses (1982)
- On Freedom's Ground (1985, to texts by Richard Wilbur)
- String Quartet No. 1 (1935; withdrawn)
- String Quartet No. 2 (1937)
- String Quartet No. 3 (1939)
- Three Score Set for piano (1943)
- String Quartet No. 4 (1950)
- Voyage: a cycle of 5 pieces for piano (1953)
- Three Piano Moods (1958)
- Amaryllis: Variations for string trio (1964)
- In Sweet Music, Serenade on a setting of Shakespeare for flute, viola, voice and harp (1978)
- American Hymn, for brass quintet (1980)
- Dances, for wind quintet and percussion (1985)
- String Quartet No. 5 (1987)
- Chester: Variations for piano (1988)
- Newsreel, in Five Shots (1941)
- George Washington Bridge (1950)
- Chester Overture (1956) from New England Triptych
- When Jesus Wept (1958) from New England Triptych
- Philharmonic Fanfare (1965), unpubd [withdrawn]
- Dedication Fanfare (1968)
- Anniversary Fanfare (1969), commissioned for the Metropolitan Museum of Art Centennial to accompany the exhibition "19th Century America" 
- Be Glad Then, America (1975) from New England Triptych
- Circus Overture, for band, arr. Don Owen (originally for orchestra—1944)
- Variations on "America", for orchestra (1963, arranged from Ives's organ piece with the same name)
- Steel Town (1944), film by the Office of War Information
- Steve Swayne (2011). Orpheus in Manhattan: William Schuman and the Shaping of America's Musical Life. Oxford University Press. Retrieved January 7, 2013.
- The New York Philharmonic Performance History Search Page
- "Music". The Pulitzer Prizes. Retrieved December 3, 2013.
- "Special Awards and Citations". The Pulitzer Prizes. Retrieved December 3, 2013.
- Lifetime Honors – National Medal of Arts.
- Finding aid for the George Trescher records related to The Metropolitan Museum of Art Centennial, 1949, 1960-1971 (bulk 1967-1970). The Metropolitan Museum of Art. Retrieved 6 August 2014.
- John W. Clark and William Schuman, "William Schuman on His Symphonies: An Interview", American Music 4, no. 3 (Autumn 1986): 328–36.
- Joseph W. Polisi, American Muse: The Life and Times of William Schuman, New York: Amadeus Press, 2008 ISBN 978-1-57467-173-5.
- Walter Simmons, Voices of Stone and Steel: The Music of William Schuman, Vincent Persichetti, and Peter Mennin, Lanham, Maryland: Scarecrow Press, 2010 ISBN 978-0-8108-5748-3.
- Steve Swayne, Orpheus in Manhattan: William Schuman and the Shaping of America's Musical Life, New York: Oxford University Press, 2011 ISBN 978-0-19-538852-7.
- Appearance On What's My Line 9/30/62 on YouTube
- The William Schuman Music Trust
- William Schuman's page at Theodore Presser Company
- William Schuman page at G. Schirmer/Associated Music Publishers
- William Schuman papers in the Music Division of The New York Public Library for the Performing Arts.
- Website for Joseph W. Polisi's book American Muse: The Life and Times of William Schuman (features streaming recordings of 10 Schuman compositions)
- NewMusicBox: A reprint of Chapter Four, "I Wanted to Run Before I Could Creep," from the book, American Muse: The Life and Times of William Schuman by Joseph W. Polisi
- NewMusicBox: "A Conversation with Joseph W. Polisi, Author of American Muse" (March 11, 2009). Joseph W. Polisi in conversation with Frank J. Oteri. (American Muse: The Life and Times of William Schuman features many photos and excerpts from William Schuman's scores)
- Website for Steve Swayne's book Orpheus in Manhattan: William Schuman and the Shaping of America's Musical Life
- Interview with William Schuman by Bruce Duffie, April 2, 1986
- William Schuman at Library of Congress Authorities, with catalog records