In December 1924 the couturier Jean Patou brought six American fashion models from New York to Paris because, he claimed, the American mannequins' lean and leggy physique was needed to sell his clothes to his American clients. This paper focuses on the American mannequins' Paris debut alongside their French counterparts in Patou's February 1925 fashion show. It explores how Patou's presentation and marketing revealed a set of wider concerns about commerce, culture, gender, and work in the 1920s. The mathematics of fashion was translated into visual seduction on the catwalk as business methods became visual and were imprinted on women's bodies. In particular, Patou's modernist styling of the mannequins' bodies pictured both the Fordist aesthetics of 1920s fashion and the Taylorist management techniques that pervaded the couture houses. In this way, Patou's modernism, rather than belonging to the artistic avant garde, was part of the social and economic rationalization of the body in the early twentieth century.