The 5th Dimension is an American popular music vocal group, whose repertoire also includes pop, R&B, soul, and jazz.

Originally known as The Hi-Fi's, the group changed its name to The 5th Dimension in late 1966 and was best-known during the late 1960s and early 1970s for popularizing the hits "Up, Up and Away", "Stoned Soul Picnic", "Medley: Aquarius/Let the Sunshine In (The Flesh Failures)", "Wedding Bell Blues", "One Less Bell to Answer", "(Last Night) I Didn't Get to Sleep at All", and The Magic Garden LP.