Juvenile delinquency became a significant social problem during the Industrial Revolution. At that time, the most frequently cited causes for the initiation and maintenance of delinquent behavior were inadequate and criminal parents and association with criminal youth and adults. Municipal leaders decided that removing delinquents and potential delinquents from their parents and from associates on city streets was the best solution to the problem. Solutions applied by policy-makers in subsequent generations have been similarly linked to popular perceptions of the causes of delinquency. The article divides the past 200 years into three phases: the creation of the juvenile justice system, the rise of Federalism, and Federalism in action. Within each phase, the article first discusses the theories of delinquency prevalent at the time and then highlights the significant theories and practices of the day. A description of the modern public policy process is followed by illustrations of how theories of delinquency are shaping policy decisions. The article concludes with speculation about how decisions in the present might influence future juvenile justice and delinquency prevention policies. Figures, notes, references