Songfacts®:

• Randy VanWarmer wrote this mellow favorite when he was just 18. It's a heartbreaker, inspired by a girl who dumped him when he was at his most vulnerable.
• VanWarmer was living in England when he wrote this song. About five years later, he landed a record and publishing deal with Albert Grossman's Bearsville Records and moved to Woodstock, New York, where the label was located, to record his first album. The first song he recorded there was "Your Light," with "Just When I Needed You Most" as the B-side. Bearsville saw a lot more hit potential in "Just When I Needed You Most," so they made that the A-side. It was a good choice: the song went to #4 on the Hot 100 and #1 on the Adult Contemporary chart.
• Recording in Woodstock had some perks, as many top musicians lived in the area. One of them was John Sebastian, who played the autoharp on the instrumental passage about two minutes in. This section was originally a synthesizer.
• VanWarmer hit the Hot 100 again with "Whatever You Decide" (#77, 1980) and "Suzi" (#55, 1981) but had more success writing for others. His song "I Guess It Never Hurts to Hurt Sometimes" was a #1 Country hit for the Oak Ridge Boys in 1984, and his "I'm in a Hurry (And Don't Know Why)" hit the top spot on that chart for Alabama in 1992. VanWarmer died in 2004 at age 48 after a battle with leukemia.
• Dolly Parton recorded this song with Alison Krauss for Parton's 1996 album Treasures. Dan Tyminski supplied harmony vocals and John Sebastian, as he did on the original, played the autoharp.