First recorded by The Buffalo Springfield (1966).
Hit versions The Mojo Men (US #36/CAN #26 1967), The Executives (AUS #28 1967).
From the wiki: “‘Sit Down, I Think I Love You’ was written in 1966 by singer-songwriter Stephen Stills, and was first recorded by his group Buffalo Springfield.
“Stills recalls he wrote ‘Sit Down, I Think I Love You’ prior to the formation of Buffalo Springfield, when he had just settled in Los Angeles and had begun writing songs that he felt ‘were personal statements and [he] had something to say.’ First recorded in 1966, it was included on Buffalo Springfield’s eponymous debut album, but because Stills had sold the song’s publishing rights, he never received any writer’s royalties. It was not released as a single.
“In early 1967, San Francisco-based group The Mojo Men released a cover version of ‘Sit Down, I Think I Love You’ as a single. Arranged by Van Dyke Parks, the song was the band’s biggest hit in the United States, peaking at #36 on the Billboard Hot 100. In Canada, it reached #26 on RPM magazine’s singles chart.
“Also in 1967, Australian pop group The Executives released their cover of ‘Sit Down, I Love You’ as a single. It peaked at #4 in Sydney, #13 in Brisbane, and #28 on the Go-Set national chart.”
The Mojo Men, “Sit Down, I Think I Love You” (1967):
The Executives, “Sit Down, I Think I Love You” lip-sync TV performance (1967):