Born in Baltimore on 31 January 1937, Philip Glass discovered music in his father's radio repair shop. The shop also sold records, and when certain records were selling poorly, Ben Glass would bring them home and have his children listen to them to figure out why customers weren't buying them. As he was soaking up the era's popular music at the same time, this was the future composer's first introduction to Beethoven's quartets, Schubert's sonatas, Shostakovitch's symphonies, as well as other works that were considered to be oddities at the time. Along with eclectic musical taste, Ben Glass was passing on business sense, and Philip would later become one of the first composers to found his own record label.

Glass graduated from the University of Chicago at the age of nineteen; his main areas of study there were philosophy and mathematics. He was then accepted at the Juilliard School, where he met Steve Reich (the two composers remained linked to each other later on, perhaps through friendship, no doubt through emulation, and, finally, through rivalry), as well as Darius Milhaud, who was then living in the United States. Glass studied with Milhaud for a short time, and the elder composer likely encouraged him in his tonal writing. In 1963, Glass traveled to France, where his studies with Nadia Boulanger required him to relearn everything from the bottom up, this time hewing to the rigor of the French approach to teaching harmony and counterpoint. He accepted occasional work, including writing music for the film Chappaqua and transcribing Ravi Shankar's improvisations. Through Shankar and the tabla player Alla Rakha, Glass developed a passion for slowly and gradually evolving repetitive structures. In 1966 he travelled to India, where he discovered the plight of Tibetan refugees and learned Hindu and Bhuddist philosophy.

Glass returned to New York in 1967, settling into the artistic life of Chelsea, notably with Reich, who by this time had already composed his own repetitive pieces - or "minimalist," to use his term - and started a music ensemble. Glass and Reich soon began playing each other's work together. Glass founded his own group, the Phillip Glass Ensemble, while supporting himself with various odd jobs, including taxi driver and plumber; he and Reich even had a moving company together. Severe minimalism, his first compositional style, was one he stayed with until the mid-nineteen-seventies, when he appeared to bring it to a close with Music in twelve Parts. At this point, he received a prestigious commission from the Metropolitan Opera for Einstein on the Beach, which brought him sudden fame when it premiered in 1976.

The 1980s were more "maximalist" than they were "minimalist," as musicologist K. Robert Schwarz has noted, and mostly occupied with the expansion of Glass's dramatic oeuvre, first with pieces written for librettos that have been described as exotic, mystical, and even New Age: first Satyagraha (1980, a Sanskrit word meaning "Holding Firmly to Truth," or "Truth Force" that Gandhi used to describe his approach to non-violent resistance) and then Akhnaten (1983, based on Egyptian, Biblical, and Akkadian mythology). Glass also continued writing orchestral pieces, notably Concerto for violin (1987).

Glass continues to compose, and his body of work includes some twenty operas, eight symphonies, and an impressive array of concert pieces and chamber music. His operatic works reached a certain high point in The Voyage (1992), composed for the five-hundredth anniversary of Christopher Columbus's landing in the Americas, thanks to a commission from the Metropolitan Opera, probably one of music history's most richly endowed. After this, among other pieces, he wrote three transversal operas that opened a kind of window onto the multidisciplinary approach he would go on to embrace - fascinating "grafts" onto Cocteau's films, based, respectively, on Orphée (1993), La Belle et la Bête (1994), and Les Enfants Terribles (1996). Glass was unique in his role as an ambassador for classical music among the stars of the pop music world, socializing and sometimes collaborating with celebrities such as Paul Simon, Susan Vega, and David Bowie. In 2007, he wrote Book of Longing, based on a cycle of songs and poems by Leonard Cohen. He also embraced the world of cinema, scoring films such as Candyman (1992), The Truman Show (1998), and The Hours (2003), as well as, more recently, Woody Allen's Cassandra's Dream. The link between popular and classical music is a thread that ran through Glass's work from the beginning, even in his early pieces, when he used the same electronic keyboards as the pop songs of the day. Terry Riley, the first American minimalist (along with his friend La Monte Young) may have been the first to draw this kind of aesthetic link, with the foundational piece In C (1964), which played constantly in the era's clubs. Glass continued in this vein, a guiding light working at the cutting edge of what has become a trend for openness and cross-pollination in contemporary music - a kind of aesthetic thaw.