This essay charts the changing definitions and experiences of sissy boys in early twentieth century America. At this time the term sissy, which had emerged out of the boy culture of mid nineteenth century America, evolved to encompass not only social but familial and clinical opprobium. In the nineteenth century, sissies might be castigated by their peers but celebrated by their families. Little boys were considered to be the province of their mothers and were not expected to adhere to strict gender boundaries. By the turn of the century, both little and older boys were held to a higher gender standard due to major transformations in child rearing, peer culture, and adult masculinity.The behaviors of little boys were closely monitored for signs of gender nonconformity as the twentieth century progressed. Even preschoolers were expected to dress in appropriately boyish clothing, to play with gender-specific toys, and to display personality traits associated with the masculine gender. "Real" or normal boys, as defined by boy culture, were postulated as ideal boys. Increasingly parents and professionals identified little boys who strayed from this ideal as in need of parental and professional intervention. The newly emerging sciences of the human psyche, which sought to explain the development of gender identity and sexual orientation, provided professionals with a framework for assessing and treating sissy boys. Together, parents, peers, and professionals worked to ensure that male children become "real boys" and not sissies.