Project Summary/Abstract While fentanyl and fentanyl analogues are the main drivers opioid overdoses in the United States, cocaine and other stimulants, like methamphetamine, are increasingly present in both opioid and non-opioid overdose deaths. These stimulant-involved overdose deaths are now central to the ?evolving overdose epidemic? or 4th wave of the overdose crisis. As Black, Latinx, and Native people face inequities in the health care system and lower access to substance use treatment, they are disproportionately affected by this stimulant-involved 4th wave. In addition, among youth, there are now more polysubstance involved overdose deaths than opioid only deaths. Post-overdose outreach programs have emerged as an important and growing response to overdose deaths by providing timely follow-up to overdose survivors and are often collaboratively implemented by public health and public safety teams. With the emerging recognition of the role of stimulants, like cocaine and methamphetamine, overdose prevention programs warrant adaptation and enhancement to address stimulant use, use disorders, and overdose risks. There is an opportunity to leverage these programs to develop and introduce adaptations for stimulant use that will provide risk reduction education and stimulant-related overdose prevention and linkage to treatment. Working within this infrastructure to partner with existing post- overdose programs, we propose to develop a toolkit of strategies to reduce stimulant-involved deaths. Each of these adaptations will be tailored to specifically engage people of color (Black, Latinx, and Native people) and youth. Our specific aims are to: (1) develop and implement a toolkit of adaptations for post-overdose outreach programs to address stimulant use and stimulant overdose overall and among people of color and youth; (2) conduct a process evaluation of the adaptations to address stimulant use in programs; and (3) determine the effectiveness of the toolkit of adaptations to: (a) increase contact with people who use stimulants, (b) reduce stimulant risk behaviors, and (c) increase treatment access for stimulant use disorder overall and among people of color and youth. Massachusetts provides a data-rich environment to ascertain the impact of post- overdose outreach on stimulant overdose. Guided by principles of community-based participatory research, we will integrate adaptive innovations to address stimulants learned from Massachusetts programs and use this information to guide and inform the design and dissemination of stimulant overdose prevention in communities across the country. The proposed research will address Objective 1, as described in the Notice of Funding Opportunity.