In the first half of the twentieth century, Americans’ intense concern with sex crimes against children led to a wave of public discussion, legislative action, and criminal prosecution. Stephen Robertson provides the first large-scale, long-term study of how American criminal courts dealt with the prosecution of sexual violence against children.Robertson describes how the nineteenth-century approach to childhood as a single phase of innocence began to shift at the end of the century to include several stages of childhood development, prompting reformers to create legal categories such as statutory rape and carnal abuse to protect children. However, while ordinary New Yorkers’ involvement in the prosecution of those offenses reshaped their understandings of who was a child and produced a new concern to establish the age of their sexual partners, their beliefs in childhood innocence and in a concept of sexuality centered on sexual intercourse remained unchanged. As a result, families’ use of the law and jurors’ decisions ultimately diminished the protection the new laws offered to children. Robertson’s study, based on the previously unexamined files of the New York County district attorney’s office, reveals the importance of child sexuality and sex crimes in twentieth-century American culture.