PETER PINDAR STEARNS was born in New York City on 7 June 1931 of musician parents. His father, Theodore Stearns, was a composer, conductor and a well-known music critic and journalist in Chicago and New York. His mother, known professionally as Marguerite Lamar, was a lyric soprano. She was a prot‚g‚e of Mary Garden and sang with the Chicago Opera Company in addition to recital work, specializing in the French chanson. Stearns' father moved his family to Los Angeles in 1932 where he had been appointed to the music faculty at UCLA. Peter grew up there and attended public and private schools in the environs of Los Angeles.

He began the formal study of music theory and composition privately with Leonard Stein at the age of fifteen, although he had already begun to compose on his own three years earlier. Returning to New York at the age of eighteen he enrolled in the Mannes Music School where he earned the Artist's Diploma in 1952. There he studied with Bohuslav Martinu in composition, Felix Salzer in theory and Schenkerian in analysis and Julia Fox in organ. After graduation from Mannes, Stearns went back to Los Angeles to work in the film industry, and studied there with Miklos Rozsa. By 1954 he was back in New York and a part of the creative life of that city.

His compositions began to appear on programs in the various concert halls of New York and elsewhere. In 1957 he was appointed to the faculty of Mannes where he remained for the next thirty-two years. He also taught briefly at Yale University and at the Wykeham Rise School in Connecticut.

Stearns and his wife, Marcia, live in Vermont