Glass showed early musical talent both on violin and flute. He graduated from the University of Chicago at the age of 19. He enrolled at Juilliard, and had by then rejected serial techniques in favor of more conventional styles, favoring the music of Ives, Copland, and Virgil Thomson. Over the next four years he studied with Persichetti, Milhaud, and Bergsma. He then studied with Nadia Boulanger in Paris, and it was during this two-year period that he met and worked with sitar player Ravi Shankar, who introduced him to Indian music. He was intrigued by its sound and structure and attracted to Asian and Middle Eastern cultures. Eventually, he converted to Tibetan Buddhism. Glass has spoken of how greatly his 1966 visit to India influenced his thinking, both musically and spiritually.
After returning to New York in 1967, Glass struggled financially and worked as a cab driver and plumber while he developed his music. He established the Philip Glass Ensemble in the early '70s. This group consisted of seven players including keyboards, woodwinds, and amplified vocals, and eventually became immensely popular both with fans of rock and the Downtown classical scene. Glass has worked collaboratively with a number of artists, including theatre director Robert Wilson, poet Allen Ginsburg, choreographer Twyla Tharp, and filmmaker Godfrey Reggio.
Glass' monumental opera Einstein on the Beach, a collaboration with Wilson, was staged in 1976 and was his first large-scale triumph, culminating with performances at the Metropolitan Opera House. It has been described as “one of the truly pivotal artworks of our time,” “among the most significant theatrical achievements of the entire post-World War II period.” It was the first of an important trilogy of biographical operas, the other two being Satygraha (based on Gandhi's struggles in South Africa, 1980) and Akhnaten (based on the 14th century BCE Egyptian pharaoh who introduced monotheism, 1983). Other operas include Orphée and La Belle et la Bête (both based on films by Jean Cocteau), The Voyage (commissioned by the Metropolitan Opera for the 1992 anniversary of Columbus' voyage), The Fall of the House of Usher, In the Penal Colony, and Kepler. Since the early 1980s, he has devoted considerable energy to film scores, which have brought his work to even larger audiences, and have been recognized with numerous prestigious nominations and awards. Among his most notable are Koyaanisqatsi and its sequels Powaqquatsi and Naqoyqatsi (written in close collaboration with Reggio), Kundun, The Hours, and Notes on a Scandal. Glass has also written in traditional Western classical forms, including nine symphonies, five string quartets, two violin concertos, and two piano concertos.