Songfacts®:

• Let It Loose was the first album from the Miami Sound Machine to give its lead singer, Gloria Estefan, star billing - a move that put Estefan on the path to stardom but also caused an irreparable rift within the group dynamic. By the time "1-2-3" climbed to #3 on the Hot 100, her husband Emilio Estefan Jr. retreated to a producing role, and the band's drummer and lead songwriter Enrique "Kiki" Garcia, who also co-wrote the track with Estefan, had quit. "There is no Miami Sound Machine," he told Rolling Stone that year. "There is Gloria and Emilio telling a bunch of hired musicians what to do."
  
  In a USA Today interview, Emilio stood by the decision to put his wife front and center: "She's been the lead singer for years but no one knows her name. They always called her 'that girl from the Miami Sound Machine.' In the Grammys, she could only be nominated in the group category, not as a singer. This was the record company's idea, and I like it."
• The song finds Gloria pining for a shy boy, and she'll keep on counting ("1-2-3-4 come on baby say you love me") until she snags him.
• A remix that included more horns and a different intro was released outside of the US in 1989. This version can be found on the albums Gloria Estefan Greatest Hits and The Essential Gloria Estefan.
• This was featured in the 1990 comedy Opportunity Knocks, starring Dana Carvey and Robert Loggia.