Spratlan joined the faculty of Amherst College in 1970, and later held the Peter R. Pouncey chair in music. He retired in 2006 and now holds the title of Peter R. Pouncey Professor of Music, Emeritus, at Amherst. He also conducted the Amherst College Orchestra for several years.
The winner of the Pulitzer Prize for Music in 2000 for a concert version of Act 2 of his 3-act opera Life is a Dream, Spratlan had begun the opera in 1975 and completed it in 1978, originally as a commission from the New Haven Opera. By the time Spratlan had finished the work, the New Haven Opera had ceased to exist and the opera was not staged.
Act 2 of the opera received its first full performance at Amherst College in January 2000, and subsequently at Harvard University. The Santa Fe Opera accepted the score for production in its 2010 season, and the complete opera received its first full production there on 24 July 2010. Spratlan wrote his second opera, Earthrise, on commission from San Francisco Opera.
Spratlan's music has been recorded/released commercially for Navona Records, Albany Records, Opus One, and Gasparo.