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.