"Didn't I (Blow Your Mind This Time)" is a 1969 single by The Delfonics, produced by Thom Bell and released on the Philly Groove record label. The recording is considered one of the most notable early Philly soul singles and is regarded as a classic, winning a Grammy Award for Best R&B Performance by a Duo or Group. Typical of the genre, "Didn't I" is a slow love ballad, with layered strings, horns, and chromatic production. Among The Delfonics' signature songs, "Didn't I (Blow Your Mind This Time)" was a #3 hit on the Billboard R&B singles chart, #10 on the Billboard pop chart in 1970, and #22 on the UK Singles Chart in 1971.

The song has been extensively covered since 1970, with versions by Aretha Franklin (from "Young, Gifted and Black" in 1971), brothers David and Jimmy Ruffin, Lisa Fischer, Regina Belle, Jackie Jackson, Millie Jackson (her version peaked #49 in the Billboard Hot R&B/Hip-Hop Songs chart,)The Trammps, Maxine Nightingale and Patti LaBelle. The song was also featured as a song that actually drives the plot in the motion picture Jackie Brown (Max hears the LP vinyl version for the first time at Jackie's house and they talk about the Delfonics as he gets to know her, then later he buys the cassette version) and was included in its soundtrack. Daryl Hall and Todd Rundgren covered this song in Episode 40 of Live From Daryl's House.

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