"I Think I Love You" is a song by Tony Romeo, written as the debut single for fictional musical TV family The Partridge Family, released in August 1970, a month prior to the debut of the ABC-TV musical sitcom "The Partridge Family" starring Shirley Jones and featuring David Cassidy, both of whom appear on the record, with Cassidy as lead vocalist. The single topped "Billboard"'s Hot 100 for three weeks in November and December 1970 and later was certified by NARM as the best-selling single of 1970.