From 1970 Sadie was editor of what was planned to be the sixth edition of the "Grove Dictionary of Music and Musicians" (1980). Sadie oversaw major changes to the dictionary, which grew from nine volumes to twenty, and was published as "The New Grove Dictionary of Music and Musicians" ("New Grove"), and is now referred to as the first edition under that name. He was also an important force behind the second edition of "New Grove" (2001), which grew further to 29 volumes. Sadie also oversaw a major expansion of the "Grove" franchise, editing the one-volume "Grove Concise Dictionary of Music" (1988), and several spinoff dictionaries, such as the "New Grove Dictionary of Musical Instruments" (three volumes, 1984), the "New Grove Dictionary of American Music", (with H. Wiley Hitchcock, four volumes, 1986), and "The New Grove Dictionary of Opera" (four volumes, 1992). He also edited composer biographies based on the entries in "Grove".<ref name="Aughor/Gale" />