A cast recording or original cast recording is a recording of a musical that is intended to document the songs as they were performed in the show and experienced by the audience. "Original cast recording" is the formal term used on record jackets (and CD cases); "cast recording" or "cast album" is the common spoken usage as of 2004.

Cast recordings are (almost always) studio recordings rather than live recordings. As the name implies they are made by the members of the original show cast, often within a few months of the show's opening. The recorded song lyrics and orchestrations are identical (or very similar to) those of the songs as performed in the theatre. Like any studio performance, the recording is of course a idealized rendering, more glossily perfect than any live performance could be, and without audible audience reaction. Nevertheless, the listener who has attended the live show expects it to be an accurate souvenir of the experience.

Prior to the development of original cast recordings, there had of course been recordings of songs from musicals, and collections of several such songs, and recordings of songs performed by cast members; but they were recordings of songs, not recordings of a musical. For example, Danny Kaye made a set of recordings of songs from Lady in the Dark. Even though Danny Kaye was a member of the cast. this was not certainly not an original cast recording—not merely because the arrangements and presentation were different, but because in this recording, Danny Kaye performed Gertrude Lawrence's songs!

The first original cast recording as we know it was probably Decca's 1943 recording of Oklahoma!. Earlier candidates exist, such as Marc Blitzstein's 1938 recordings of songs from The Cradle Will Rock. The Decca album, however, was a huge commercial success and was systematically followed up by further recordings from Decca, and, soon, all the other record companies. Cast recordings were particularly well suited for the then-new Columbia Records LP and in the early 1950s Columbia ascended to leadership and Columbia's cast recordings came to define the genre.

A 1970 documentary by D. A. Pennebaker, Original Cast Album—Company (http://www.imdb.com/title/tt0293475/) gives a straightforward view of the making of a cast recording. It shows how the recording studio looks, how performers are arranged, and how the director behaves. The cast feels the pressure of delivering a definitive performance, with a degree of perfection beyond that ever required on stage, under a time limit imposed by the high cost of studio time.

Vinyl LP cast recordings were usually released as single discs, and it was not rare for compromises to be made to fit the recording within the forty-to-fifty-minute time limit. For example, obscure songs might be not be included. In the 1980s, the rise of the Compact disc with its 74-minute recording capacity (which was increased to 80 minutes in the 1990s) resulted in improvements in cast recordings, which were now usually capable of including all songs, the full overture and entracte, and, when appropriate, lead-in dialogue to the songs.