David Rosen (born September 21, 1938, in San Francisco^[1]) is an expert in nineteenth- and early twentieth-century Italian opera. He is noted for having discovered the complete score of Messa per Rossini, presumed lost, in the archives of the Italian music publishing house G. Ricordi & Co in 1986.

He was responsible for the critical edition of Verdi's Messa da Requiem^[2] and the Cambridge Music Handbook on the Requiem.^[3] He also discovered in the Bibliothèque Nationale a passage in Verdi's manuscript score for Don Carlos which had had to be cut in order to ensure that the opera's premiere would finish before midnight. This led to a further discovery of more music which had also been discarded.^[4]

Rosen has also pursued an interest in understanding the original staging of late romantic opera, publishing a seminal work on the staging of Un ballo in maschera.^[5] He is an emeritus professor of musicology in the Department of Music at Cornell University. He has worked also with the Centro studi Giacomo Puccini and the Fondo Leoncavallo.