"I Knew You When" is a song written by Joe South and was recorded by Billy Joe Royal for his 1965 album, Down in the Boondocks. The song reached #14 on The Billboard Hot 100 in 1965. The song went to #1 on the Canadian music chart in November 1965.
Joe South would later record his version of the song for his 1969 album, Games People Play.
Donny Osmond released a version in 1972 as the B-side of "Hey Girl" that went to #9 on the Hot 100 as a double-sided hit.
Linda Ronstadt recorded a version on her 1982 album, Get Closer It reached #37 on the U.S. chart when released as the album's second single. It also reached #29 on the adult contemporary chart, #84 on the country chart, and #90 in the U.K.