During the late 1940s, John Derro was working as a costume designer on Broadway before transitioning into women's ready-to wear in the early 1950s. For the manufacturer Mainstreet he designed high-end women's rain gear before the company placed him at the helm of their Young Couture subsidiary line. In 1958, he was honored by Bloomingdale's as a top young American designer. Sometime around 1962, Derro left Mainstreet for the head design position at the 7th Avenue label David Hart. In 1963, following the retirement of Evelyn Dawson, Derro became the designer for the Suzy Perette line, which Dawson and a partner had established.