The Delfonics are an American R&B/soul vocal group, primarily active during the late 1960s and early 1970s. Known for their smooth, harmonic blend and dramatic arrangements, they significantly contributed to the "Philly Soul" sound. Key members included brothers William and Wilbert Hart, and Randy Cain, with William Hart serving as the primary songwriter. Their most influential works include hits like "La-La (Means I Love You)" and "Didn't I (Blow Your Mind This Time)", both of which exemplified the soulful, emotive performances that became a hallmark of their style.