The original “Happy Days” theme by Jim Haas (and other session singers) was not the show’s opening theme — rather, it was the closing theme for the first two seasons, with Bill Haley & His Comets’ “Rock Around the Clock” aptly playing during the opening credits. (You can’t get any more ’50s than that tune.) As such, it’s quite likely that the version you recognize is the one performed by Pratt & McClain, as this was the one used from Season 3 through 10 of “Happy Days,” during both the opening and closing credits.
According to the duo’s AllMusic biography, Truett Pratt and Jerry McClain first met in the early 1970s and were originally known as Brother Love — this was no conventional pop-rock duo, as one may surmise from their involvement in the longest-running version of the “Happy Days” theme. Rather, the two musicians recorded commercial jingles before releasing an album on Dunhill Records under their surnames. After getting signed to Reprise Records, Pratt & McClain were enlisted to record a new take on “Happy Days” with rewritten lyrics, and the re-recorded track proved to be so popular that it went all the way to No. 5 on the Billboard Hot 100 in the spring of 1976.
Pratt & McClain would turn out to be one-hit wonders, as their only other Hot 100 single, a cover of Mitch Ryder & the Detroit Wheels’ “Devil with the Blue Dress On,” only peaked at No. 71.
