From the late 1950s through the early '60s, the pop charts were full of street corner harmony as scores of vocal groups formed and hit the recording studios. Drawing on the grandfathered styles of the Mills Brothers and the Ink Spots, and later the Ravens and the Orioles (which led to a grand procession of groups named after birds), these quartets and quintets added in a little gospel plus a slight dose of the old jump blues and hooked themselves to the rock & roll train as it flew past. In time, the grittier R&B roots were smoothed out for the teen market, and doo wop -- an umbrella term for all of these vocal incarnations -- was well on its way to becoming its own sort of instant, self-referencing nostalgia when the Beatles and the British Invasion hit to finish the matter. This three-disc set spreads its net fairly wide to include some early Motown acts as well as groups like the Platters and the Drifters who are probably closer to mainstream R&B than they are to doo wop proper, if you're into splitting hairs. Either way, the end result is an impressive starter box for the genre, although a few tracks from the Mills Brothers, the Ink Spots, the Ravens, the Orioles, and the other late-'40s vocal groups who helped set the template for the harmony group form would have made a nice fourth-disc addition.