"Didn't I (Blow Your Mind This Time)" is a song co-written by record producer Thom Bell and William Hart, lead singer of the American R&B/Soul vocal group the Delfonics. It was released by the group in 1969 on the Philly Groove record label and is regarded as a classic, winning a Grammy Award for Best R&B Vocal Performance by a Duo or Group. It is considered one of the most notable early Philly soul singles and typical of the genre, "Didn't I" is a slow love ballad, with layered strings, horns, and chromatic production. Overseas the song peaked at number 22 on the UK Singles Chart in 1971.