["Addiction, Volume 121, Issue 7, Page 1747-1760, July 2026. ", "\nAbstract\n\nBackground and aims\nThe opioid crisis is still a public health emergency in the United States, despite recent declines in opioid overdose deaths (OODs) and increased availability of evidence‐based practices (EBPs) for opioid use disorder (OUD). The geographic variability in OODs drives the need for localized decision‐making, where interventions are tailored to the unique needs of communities. This study aimed to develop and calibrate a simulation model that evaluates the impact of enhanced implementation of EBP on OODs at the community‐level.\n\n\nDesign\nWe developed OPSiM (Opioid Policy Simulation Model), a community‐level microsimulation model that simulates the course of opioid use, OUD, treatment, recovery and overdose‐related events. The model was parameterized with data from the HEALing Communities Study and looked at six scenarios of EBPs implemented in 2025 with sustainment through 2030: (1) maintain 2024 EBP levels (status quo); (2) increase initiation of medications for opioid use disorder (MOUD); (3) increase MOUD retention; (4) increase MOUD initiation and retention; (5) increase distribution of naloxone; and (6) both scenarios 4 and 5.\n\n\nSetting\nTwenty‐nine communities in Massachusetts, New York, and Ohio, USA.\n\n\nParticipants\nSimulated community residents with non‐prescribed opioid use or OUD.\n\n\nMeasurements\nEstimated number of OODs per 100 000 individuals between 2025 and 2030 in each community, averaged across the 26 communities.\n\n\nFindings\nUnder the status quo, the model projected 158 OODs (range across communities: 39–468) per 100 000 individuals between 2025 and 2030. Increasing medications for the treatment of OUD (MOUD) retention alone reduced OODs by 6% (range: 3–15%), while increasing MOUD initiation alone reduced OODs by 9% (range: 8–12%). Increasing both MOUD initiation and retention had a synergistic effect, reducing OODs by 21% (range: 15–31%). Reduction in OODs in response to increased MOUD initiation and/or retention was similar across urban and rural communities. The effect of increasing naloxone distribution varied substantially across communities due to differing saturation levels; in some communities, additional naloxone kits provided only marginal benefits. Rural communities were further from saturation whereas most urban communities were at or close to saturation.\n\n\nConclusions\nA tailored, multi‐pronged approach that scales up medications for opioid use disorder alongside widespread naloxone distribution, and that addresses community‐specific needs and capacities, will be most effective at reducing opioid overdose deaths in the United States.\n\n"]