The main group of actors -- Emilio Estevez, Ally Sheedy, Demi Moore, Judd Nelson, Andrew McCarthy and Rob Lowe -- were at the peak of their popularity. They were young, good looking, wealthy, and they loved to party.
"I've worked with Judd and Ally before, and I've worked with Rob before, and I knew Demi before we started shooting," Emilio told ET at the time.
The movie was a reunion for Judd, Ally and Emilio, who starred together in The Breakfast Club, which was released just months before St. Elmo's.
"I feel so comfortable with them already," Ally told ET at the time. "I feel like Emilio and Judd are brothers to me."
Andrew lived vicariously through his character in the film, as he didn't get the normal dorm life experience.
"I went to college for two years in New York, so I didn't have a real college experience, but the same kind of madness goes on with the whole group of us when you go out with everyone," he said.
The Brat Pack, as they were called, had a blast when they were together, but after St. Elmo's, it was rare for more than two co-stars to share the screen later on.
"I feel comfortable enough within myself to come out and say, 'Alright guys, let's go at it in a competitive way, in the healthiest sense,' you know?" Rob said. "It's like, 'Alright, I dare you to be as good as me.' The other says, 'I dare you to be as good as me,' and it's great."