Personnel includes: Donna Summer (vocals); Dino Solera (saxophone); Giorgio Moroder (Moog synthesizer); Keith Forsey, Josef Spector, Bob Conti, Pete Bellotte, Bob Esty (percussion).

Although disco is primarily thought of as a singles-based music, Donna Summer and her primary collaborators, Giorgio Moroder and Pete Bellotte, indulged in some fairly ambitious concept albums that belie that simplistic assertion. ONCE UPON A TIME is one of their most wide-ranging efforts, a double-album modern-day fairy tale that truly only makes sense when listened to as a whole, rendering Summer's inter-song narration and Moroder and Bellotte's use of repeated musical elements much more effectively. Of course, this didn't really help the album reach its dance-floor audience; it was a comparative flop, with the single "I Love You" barely cracking the Top 40. In retrospect, however, ONCE UPON A TIME has become a firm fan favorite, with the anthemic "Queen for a Day" and the funky-yet-symphonic title track among Summer's most beloved songs.