During the Progressive Era, young working class women were sometimes jailed for engaging in social and sexual activities that signaled their rejection of Victorian moral standards. These disadvantaged "delinquents" were subject to legal sanctions rarely applied to middle class girls. The author observed a great deal of inequality and cultural conflict in female adolescence but found that most delinquent young women eventually accepted the idea that freedom was best won by conformity and accommodation. In showing how a new social problem was identified and tackled, the author also documents the emergence of the modern professions of social work and mental hygiene. She examines how and why working class, immigrant, and nonwhite women were arrested and incarcerated as delinquents and the values, expectations, and methods of reformatory officials. The historical review of individual women incarcerated in reformatories during the 1900-1930 period particularly focuses on the interplay among girls and the role of families, courts, and penal institutions. Notes