Sadie is credited with remaking the titanic reference work, opening it to articles about jazz, rock, and world music, and increasing it from nine volumes to 20. The sixth edition, which Sadie began in 1970 and published in 1980, was so different from the previous edition that the title was amended with the epithet "new." The dictionary's most recent edition, which came out in 2001, was 29 volumes.

The London-born Sadie received his bachelor's, master's, and doctorate degrees from Cambridge University, and taught at London's Trinity College of Music for eight years. He wrote reviews for the Times of London and for the magazine Gramophone, and in 1967 became editor of Musical Times, a musicological journal, where he stayed until 1987.

His other published works include studies of Handel and Mozart. His final book, Mozart: The Early Years, 1756-1781 will be published in December by Norton; Words About Mozart: Essays in Honour of Stanley Sadie, a collection of essays by his colleagues, was published earlier this year.

With his second wife, musicologist Julie Anne Sadie, he lobbied to save Handel's London house, which led to the creation of the Handel House Museum.