“Heart of Glass” existed in Blondie’s live repertoire as far back as 1975 under the title “Once I Had a Love”. The song that eventually became their major crossover and biggest hit (or “sell-out” as the New York punk scene angrily dubbed it) originally had a plodding reggae beat. It continued to evolve through 1978, first into a sped up rock rant, and finally, with an overhaul by producer Mike Chapman for album Parallel Lines, a disco classic. The single was released in January 1979 and climbed to #1 in both the U.S. and UK. Its accompanying music video was shot at center of the disco universe, Studio 54, only accentuating a direction their peers reviled. Despite the brief pariah status within the punk scene, Debbie Harry to this day shrugs off the fleeting criticism, pointing out that Blondie always pursued off-kilter takes on a variety of pop styles. The band has jokingly referred to the song as “The Disco Song” in interviews.

Live BBC Concert from 1979
Performing “Heart of Glass” on the Today Show in 2007 with Lily Allen
Official Blondie Website
Official Debbie Harry Website
Extensive Fan Archive