OBJECTIVES: In 2016, the Centers for Disease Control and Prevention supported 5 local health departments (LHDs) to implement teen dating violence and youth violence primary prevention strategies across multiple levels of the social-ecological model and build capacity for the expansion of such prevention efforts at the local level. The objective of this study was to estimate the total cost of implementing primary prevention strategies for all LHDs across 3 years of program implementation. METHODS: We used a microcosting analytic approach to identify resources and compute costs for all prevention strategies implemented by LHDs. We computed the total program cost, total and average cost per strategy by social-ecological model level, and average cost of implementation per participant served by the program. All costs were inflated via the monthly Consumer Price Index and reported in August 2020 dollars. RESULTS: For 3 years of program implementation, the total estimated cost of implementing teen dating violence and youth violence primary prevention strategies was >$7.1 million across all 5 LHDs. The largest shares of program-related costs were program staff (55.9%-57.0%) and contracts (22.4%-25.5%). Among prevention strategies, the largest share of total costs was for strategies implemented at the community level of the social-ecological model (42.8%). CONCLUSIONS: The findings from this analysis provide a first look at the total costs of implementing comprehensive teen dating violence and youth violence primary prevention strategies and serve as a foundation for investments in local violence prevention funding for young people.