The HD2A Modeling and Economic Resource Center (MERC) provides expertise and consultation on simulation modeling and economic evaluation methods to support the HD2A Innovation Projects and conduct original research. The Center hosts a consultation service on the selection and use of research methods, including economic evaluation, simulation modeling, advanced statistical analysis, behavioral economics, treatment program organization research, and cost analysis. The RESPOND model (a dynamic population compartmental simulation model of opioid use disorder) enhances data-driven decision-making. The MERC provides online training resources, methods for assessing economic benefits, systematic reviews of costs and cost-effectiveness of evidence-based practices, program cost assessment tools, individual-level cost assessment questionnaires, budget impact tools, and costing tools to inform payment design. Investigators conduct a comparative and meta-modeling research project, conduct an innovative payment design research project focused on peer recovery support services, and conduct additional delayed-onset original research projects.