"Reason to Believe" is a song written, composed, and first recorded by American folk singer Tim Hardin in 1965. It has since been recorded by artists including the Carpenters in 1970 and Rod Stewart in 1971 and 1993.

After having had his recording contract terminated by Columbia Records, Tim Hardin achieved some success in the 1960s as a songwriter based in Greenwich Village. The original recording of "Reason to Believe" comes from Hardin's debut album, Tim Hardin 1, recorded in 1965 and released on the Verve Records label in 1966 when he was 25.

Tim Hardin's original recording of the song is also on the soundtrack to the 2000 film Wonder Boys.

The Carpenters recorded "Reason to Believe" for their second LP, Close to You, in 1970. On television, they performed it on the The 5th Dimension Travelling Sunshine Show on August 18, 1971 and Make Your Own Kind of Music on September 7, 1971. Richard Carpenter remixed the song for the release of the 1995 compilation, Interpretations: A 25th Anniversary Celebration.

Rod Stewart's version appeared on his 1971 album Every Picture Tells a Story. It was the first single from the album with "Maggie May" as the B-side. "Reason to Believe" reached No. 62 on the Billboard Hot 100 on its own before the more popular B-side overtook it on its way to No. 1 on the chart.

A live version was released in 1993 on the album Unplugged...and Seated. Released as the second single from the album, it reached No. 19 on the Billboard Hot 100. The 1993 single includes a live version of "It's All Over Now", which was recorded during the MTV Unplugged performance but does not appear on the album.

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