PROJECT SUMMARY Opioids were involved in almost 47,000 deaths in the U.S. in 2018—nearly the number who were killed in the entire Vietnam War. Injection opioid and methamphetamine use are driving up rates of HIV and HCV infection. The opioid crisis has similarly affected Canada and Mexico, leading to a call for a North American approach to addressing the opioid crisis. Simulation models provide a structured environment for decision makers to compare the predicted effects of proposed policy alternatives over an extended time horizon on population- level outcomes such as overdose, HIV, and HCV. The COVID-19 pandemic has provided evidence of the utility of using simulation models for public health decision making. Several public agencies are currently funding opioid simulation modeling efforts in North America, including NIDA, CDC, FDA, the Canadian Institutes of Health Research (CIHR), and Canadian provincial agencies. Our overarching goal is to improve the speed, validity, effective knowledge translation, and