In the 1930s and 40s, what had been as a gospel and vaudeville vocal style was adopted to popular songs, and the rich tradition of four-part harmony reached its peak-and The Mills Brothers and the Delta Rhythm Boys were the premier groups that captured America's attention. 'Sing Brother Sing' includes 18 rare, early appearances by these two supergroups, including the Ohio-born Mills Brothers' 1932 hit 'St. Louis Blues,' their 1943 hit 'Paper Doll' which became one of the biggest hits of the decade, and their 1944 #1 hit 'You Always Hurt The One You Love.' The DRB's 1941 hits 'Dry Bones' and 'Take The A Train' are very fine. Other winners are 'Jack You're Playing The Game,' a small movie in itself, 'Opus One,' featuring the Mills Bros. with Nat King Cole,' 'Lazy River,' 'Till Then,' 'Caravan' (check out the early vocal percussion and vocal horns) and 'Swing Brother'-but there's really not a weak cut. Besides enjoying the butter-smooth harmonies, it's fascinating to watch the dancing and acting in the little skits that illustrate the songs. What is clear throughout is the sheer vocal power and hip sophistication of these pioneer groups, whose musical stylings laid the groundwork for every Pop and Soul group to follow. These gems may be thought of as early MTV videos, documenting two groups that are a source for much of the great music that has touched our lives.