Youth justice is a challenging environment in which to implement a rigorous PYD approach. The insights and lessons of developmental science do not translate easily into the day-to-day tasks of youth justice systems, which often focus on control and compliance. Youth justice practitioners require assistance as they apply developmental principles. The Positive Youth Justice (PYJ) Model was developed to meet this challenge. It provides a simple framework for designing PYD-compatible interventions for justice-involved young people and for supporting youth justice reforms.