In the antebellum United States, law and public opinion defined adult independence as a stage of life specific to white men, while classifying white women as perpetual dependents. In response, woman's rights activists used age-based schedules of human development to challenge laws and social customs that treated women like minors, and to claim rights and opportunities for women as they entered adulthood and grew old. This analysis of antebellum political discourse revises the history of aging in two ways. First, it demonstrates that, while the ages at which people left school, married, and began work remained widely variable, age twenty-one nonetheless was defined as a significant transition to independence for white men, though not for white women. Second, it shows that state governments used chronological age to regulate the transition to independent citizenship long before the development of other age-based programs such as child labor laws and social security.