What You Don't Know is the second album by Exposé, released in June 1989. It appears both in cassette and CD formats. The remixes of "What You Don't Know" and "When I Looked at Him" are available only on the CD.
Unlike the previous album, this one focuses on the vocals of Gioia Bruno, as she sings lead vocals on half of the tracks. She only sang lead vocals on 3 of the tracks from Exposure. Curless sings lead on two tracks ("Stop, Listen, Look & Think" and "Now That I Found You"), Jurado on three ("When I Looked at Him," "Still Hung Up on You," and "Your Baby Never Looked Good in Blue").
Five singles were released from this album. "What You Don't Know", "When I Looked at Him", and "Tell Me Why" all peaked within the top 10 of the Billboard Hot 100, at #8, #10, and #9, respectively. "Your Baby Never Looked Good In Blue" peaked within the top 20 at #17. "Stop, Listen, Look, and Think" was released solely to dance clubs and as a 12-inch single.