Sex trafficking is a state crime. Nevertheless, it is also a federal crime when it involves conducting the activities of a sex trafficking enterprise in a way that affects interstate or foreign commerce or that involves travel in interstate or foreign commerce. Section 1591 of Title 18 of the United States Code outlaws the activities of sex trafficking enterprise that affects interstate or foreign commerce, including patronising such an enterprise. The Mann Act outlaws sex trafficking activities that involve travel in interstate or foreign commerce. This book provides an overview of sex trafficking. It focuses on the sex trafficking of children in the United States and reviews the Preventing Sex Trafficking and Strengthening Families Act.