The Rooftop Singers were the most successful of the folk revival's one-hit wonders -- their single major chart entry, "Walk Right In," was a number one record and also the biggest-selling single in the history of their label, Vanguard Records. The group was a trio consisting of Erik Darling, Bill Svanoe, and Lynne Taylor, formed in late 1962. Darling had been Pete Seeger's successor in the Weavers from 1958 through 1962, and had previously worked as a member of a jazz-folk influenced trio, the Tarriers, who had a modest hit with "Banana Boat Song." He had also appeared on doze...