Having developmental competence means understanding that children and adolescents’ perceptions and behaviors are influenced by biological and psychological factors related to their developmental stage. For adults working with young people, taking a developmental approach could lead to better outcomes for kids. In fact, the National Research Council recently published a report calling a developmental approach the key to reforming juvenile justice. And four recent U.S. Supreme Court decisions were grounded in an understanding of the developmental changes in adolescents’ brains — and state courts are following suit. Yet the question remains: How do we convince adults who work with youth to take a developmental approach?