The Delfonics were one of the first groups to sing in the sleek, soulful style that became popularized (thanks to producer Thom Bell) as the "Philadelphia sound." A vocal trio made up of brothers William and Wilbert Hart and high school friend Randy Cain, the Delfonics roots go back to doo wop singing at school dances in the early '60s. They were well-known in the Philly area for their supple, airtight harmonies talent that brought them to the attention of record producers, eventually landing them a contract with Cameo-Parkway. While their early records brought them little if any notice, it did bring them to the attention of producer/arranger Thom Bell who signed the band to his soon-to-be influential soul label Philly Groove. Right from the start this was a perfect match as the band released the classic "La La Means I Love You" in 1968, a song that began a string of hits lasting into the mid-'70s.
The sound that Bell created for the Delfonics was the antithesis of the soul sound that came from Stax in Memphis and Muscle Shoals in Alabama. He sandpapered away the grit, lightened up on the backbeat, brought in string sections, and created a smooth, airy sound. Critics enamored of the soul singing of Wilson Pickett and Otis Redding accused Bell and his groups of creating aural wallpaper, but the reality was that Bell and the Delfonics were setting the stage for a different kind of groove where subtlety and nuance reigned.
The hits slowed for the Delfonics in the mid-'70s, and in 1971 Randy Cain quit the band and was replaced by Major Harris. A few more minor hits followed but Harris left the band for a solo career in 1975, effectively finishing the Delfonics. In the late '90s, the group played a significant musical role in Quentin Tarantino's film Jackie Brown. Tarantino, a borderline obsessive fan of '70s pop culture, used "La La Means I Love You," and their best single, "Didn't I (Blow Your Mind This Time)," as a way of underscoring the relationship between actors Pam Grier and Robert Forster. In the film, Forster's character is so struck by the music (and Grier), he goes out and buys the Delfonics Greatest Hits cassette the following day. Something I'd recommend you do too. John Dougan, All Music Guide
Source: http://www.starpulse.com/Music/Delfonics,_The/Biography/