The HEAL Data2Action (D2A) Program is a coordinated effort to promote the synthesis and real-world application of existing data to guide and monitor improvements in service delivery to prevent or treat opioid use disorder (OUD) and pain. Collectively, these projects will address gaps in the delivery of evidence-based practices in each of the four pillars of the HHS Overdose Prevention Strategy: primary prevention, harm reduction, treatment of opioid use disorder, and recovery support. The HEAL D2A Modeling and Economic Resource Center (MERC) will support the HEAL D2A Innovation Projects by providing expertise in simulation modeling and economic evaluation methods and will consult with the HEAL D2A Innovation Grant recipients on applying these methods and insights in their local implementation activities. The MERC will also conduct original research applying state-of-the-art economic and simulation modeling expertise to understand and address the overdose crisis. Since 2015, we have worked collaboratively to lead a highly successful multi- institutional NIDA-funded national center of excellence, the Center for Health Economics of Treatment Interventions for Substance Use Disorder, HCV, and HIV (CHERISH). We are thus uniquely qualified to lead the HEAL D2A MERC with the following aims: 1) to support the HEAL D2A Innovation Projects by providing methodological consultation on the application of rigorous modeling techniques, cost analyses, and behavioral economic strategies to support the projects' selection and implementation of evidence-based practices to address service delivery needs; 2) to develop tools that can be readily used by the Innovation Projects to make informed decisions about the relative costs of different implementation interventions to different stakeholders, to measure the overall costs of these efforts, and to inform the design of appropriate payment systems that support sustainability; 3) to use meta-modeling techniques to develop a user-friendly interface so that simulation model results generated for one system or community can be adapted for other systems/communities or adapted when local circumstances change; 4) to conduct novel research using advanced modeling and health economics approaches that build on existing data to provide insights into the complex dynamics of addressing the overdose crisis through strategic implementation of evidence-based practices. The HEAL D2A MERC will support the application of health economics and modeling research to real-world decision making about services to prevent or treat opioid use disorder and pain, will further scientific innovation in the field, and will establish a paradigm for integrating health economics and modeling into substance use treatment and prevention policies at the system level. The HEAL D2A MERC will be collaborative with the work of the HEAL D2A Research Adoption Support Center (RASC), including the consultations and catalog of measures and tools of the Implementatio...