Contrary to Anthony Platt's contention that juvenile court laws passed after 1899 brought under governmental control a set of youthful activities that had been previously ignored or handled informally, many states had similar laws for many decades. In fact, those who dealt with children in the 19th century were obsessed with curtailing noncriminal juvenile misconduct and their concerns increased during the course of the century. In addition, they showed much less concern for children who committed serious crimes. The creation of juvenile courts did not contribute new concepts to juvenile jurisprudence. Instead, it provided a more effective means for implementing an approach to wayward children that had existed for most of the 19th century and that had become the main approach to youth by 1900. Moreover, the legal developments of the 19th century created a legal framework for a concept of adolescence as a developmental stage distinct from adulthood. Thus, the current system assumes both that a progression exists from youthful misbehavior to criminal activity and that the youth's deviance rather than external factors such as poverty, schools, or the family situation require change. Appended tables and 387 footnotes.