Objectives: Describe the developmental trajectory of perceptions of the police by youth as they transition from adolescence to young adulthood. Method: A longitudinal experiment to evaluate the impact of the D.A.R.E. program (N = 1,773). Latent variable growth modeling was used. Results: A dramatic decline in the favorable attitudes of youth toward the police begins in about seventh grade. More negative perceptions of police are associated with minority racial status, negative experiences with officers, involvement in the delinquent subculture, and greater expressions of skewed legal norms. There is a long-term positive effect of D.A.R.E. on attitudes toward the police, particularly for African American youth. Conclusion: The study highlights the importance of theorizing about perceptions of the police from a life course perspective. Findings raise new policy questions about the long-term impact of school-based programs, such as D.A.R.E., and the role of multiple reference groups in the formation of minorities’ attitudes. More research is needed to gain a better understanding of the cognitive and experiential processes involved in attitude formation.