"California Soul" is a pop-soul tune written by Ashford & Simpson, issued originally as a "B" side of The Messengers single, "Window Shopping" in 1967 under the Motown group of labels. The Messengers' sound was Monkees-based pop, see Complete Motown Singles, Volume 7. It was then issued as a single by American pop quintet The 5th Dimension in late 1968, and also covered by Motown vocal duo Marvin Gaye and Tammi Terrell and Marlena Shaw the next year. It was Marvin's and Tammi's last single together when released in early 1970.
Both the 5th Dimension's version and the Gaye/Terrell version were modest charted hits. The 5th Dimension's performed better, reaching number twenty-five on the pop singles chart, while Marvin and Tammi's cover reached number fifty-six pop but never charted R&B. The duet was released after Terrell's death from a brain tumor in March 1970.