On this day in 1977, Hollywood composer Bill Conti scores a #1 pop hit with the single “Gonna Fly Now (Theme From Rocky).”

Bill Conti was a relative unknown in Hollywood when he began work on Rocky, but so was Sylvester Stallone. Conti had gained some attention internationally with his work on several early 1970s Italian films, including Vittorio de Sica’s Academy Award-winning Il Giardino dei Finzi-Contini, and Stallone had starred in a small film called Lords of Flatbush and played various minor roles in movies and on TV. It was Rocky that would truly launch both men’s careers, though. The film was Stallone’s from start to finish—he wrote and directed it as well as playing the starring role—but it is difficult to overstate the importance of his collaboration with Conti. Though Conti took his inspiration from Stallone’s footage, Stallone had the film’s critical training and fight sequences edited to fit Conti’s music, and the interaction between picture and music in Rocky made an enormous contribution to the movie’s success.

The single “Gonna Fly Now” takes its name from the almost-superfluous 30 words of lyrics written by Ayn Robbins and former Teddy Bear Carol Connors. Though it lost the competition for Best Original Song at the 49th Annual Academy Awards to Barbra Streisand and Paul Williams’ “Evergreen (Love Theme From A Star Is Born),” it has remained an instantly recognizable piece of American pop culture. In the years since the release of Rocky, Sylvester Stallone has continued to churn out action flicks, and Bill Conti has built a hugely successful career as a composer for film and television—a career that eventually included an Academy Award for Best Original Score for the 1983 film The Right Stuff.