In music, sostenuto is a term from Italian which means "sustained," and occasionally also implies a slowing of tempo. It usually refers to a style of playing rather than a tempo; for instance, if the tempo marking of a piece is Adagio Sostenuto, the tempo would be slow (Adagio), and the sostenuto part of the marking tells the player to hold notes longer than he normally would, and perhaps also to play longer phrases than might normally be the case.

On a modern piano with three pedals, the middle pedal is called the sostenuto pedal. It sustains notes only which are depressed at the time the pedal is depressed. On some upright pianos, the middle pedal sustains all notes in the bass register, but this is not a true sostenuto pedal. Note that the sostenuto pedal should not be confused with the much more commonly used sustain pedal, which undamps all the strings on the piano.