The Drug-Free Communities (DFC) Support Program aims to reduce youth substance use by fostering multi-sector collaboration and implementing locally tailored strategies within the community. This study is among the first to evaluate the program's impact on youth development outcomes in the United States. Using the Callaway and Sant'Anna (2021) difference-in-differences (CSDID) estimator, we find that the DFC program significantly reduces drug-related juvenile crime and improves academic performance. The effects are particularly pronounced in communities where coalitions include government agencies, highlighting the critical role of institutional coordination in mobilizing local resources. We also explore behavioral mechanisms, documenting reductions in marijuana use and opioid-related inpatient hospitalizations. A cost-benefit analysis indicates substantial welfare gains, suggesting that early-life prevention represents a cost-effective investment in public health.