Songfacts®:

• The expression "what you don't know won't hurt you" means you're best off blissfully unaware of any disturbing news. But in this song, what you don't know can hurt you - when it comes to love.
  
  The singer is crazy about a guy, but he's non-committal. Because he doesn't know how she feels, he might keep playing it loose, and she just might leave. What he doesn't know might hurt him.
• Exposé were leaders in high energy dance music, adapting the freestyle sound to give it more pop appeal. "What You Don't Know" was written by their producer, Lewis Martineé, who assembled the group in 1983. Martineé wrote every song on their 1987 debut album, a smashing success with the upbeat tracks "Come Go With Me," "Point Of No Return," and "Let Me Be The One," as well as the ballad "Seasons Change." "What You Don't Know" was the lead single and title track to their next album, and it continued their run of hits, giving them five consecutive Top 10 singles. Their next two singles, also written by Martineé, were "When I Looked At Him" and "Tell Me Why." They also entered the Top 10, making it seven in a row.
• There were many girl groups competing in the dance music genre at this time, but something that set Exposé's songs apart from the likes of Sweet Sensation and The Cover Girls was their use of organic instruments. "What You Don't Know" has a guitar solo and a horn section, giving some shape to the electronic beats. This gave the song plenty of appeal outside of the dance clubs.
• Group member Gioia Bruno took the lead vocals on this one, as she did on "Let Me Be The One." Most of Exposé's lead were sung by Jeanette Jurado.
  
  All three members of the group at this time came in after Exposé earned their record deal with Arista, replacing the original three during recording of their first album. Bruno developed throat problems and left before their next album was released in 1992, but that album ended up being their last, and they broke up a few years later when Arista dropped them. When the group started performing again in the mid-'00s, Bruno came back into the fold.
• In the music video, the ladies ditch their guys, who are preoccupied watching a baseball game, to perform the song with their band. When they return, it's clear these guys have no idea they lead a second life as pop stars.
  
  The video was directed by Greg Gold, who also did Brenda Russell's "Piano In The Dark" and Smokey Robinson's "Just To See Her."