Background: Drug overdose is a leading cause of death, accounting for 70,630 deaths in the United States (US) in 20193. The majority of drug overdoses involve opioids, and opioid-involved stimulant deaths are rising with 3 out of every 4 cocaine-related deaths involving opioids and 53% of psychostimulant-related deaths involving opioids7. Drug overdose mortality among Veterans mirror these trends5,6. In Massachusetts, among individuals who died of an opioid overdose, 1 in 6 had a non-fatal overdose in the preceding 12 months17. These non-fatal overdoses serve as a promising target for opioid overdose prevention efforts, especially for evidence-based treatments such as medications for opioid use disorder (MOUD). The increase in stimulant- involved opioid overdoses also highlights the need to investigate strategies to improve uptake of evidence- based treatments for stimulant use disorders. Significance: In March 2019, the VHA Office of Mental Health and Suicide Prevention released a national clinical note template, the Suicide Behavior and Overdose Report (SBOR). The SBOR standardizes the reporting process, enhances the visibility of suicide and overdose events in the medical record, and is intended to improve clinical care after these events (e.g., by incorporating risk factors for overdose and strategies to mitigate risk, including referrals for care). However, the SBOR is currently mandated for intentional overdose and only recommended for unintentional overdose. Moreover, it is unclear the extent to which it is being used and whether its use improves post-overdose care as intended. Innovation and Impact: The proposed study will characterize non-fatal opioid-, stimulant-, and combined opioid and stimulant overdoses among VHA patients and the extent to which they receive recommended post- overdose care. Given that the SBOR will soon be mandated for all overdoses, and to ensure that VHA is doing everything it can to prevent overdose mortality among Veterans, it is critical to understand whether the SBOR is improving post-overdose care as intended and if additional strategies may be needed. Specific Aims: The proposed study will pursue the following specific aims: Aim 1: Characterize non-fatal opioid and/or stimulant overdoses within VHA and patient-, prescriber-, and setting-related factors associated with post-overdose treatment utilization. Aim 2: Describe utilization of the SBOR among providers of patients with non-fatal opioid and/or stimulant overdoses and associations between SBOR use, post-overdose treatment utilization, and treatment outcomes. Aim 3: Identify barriers and facilitators of post-overdose care and ways to improve it via interviews with VHA patients, patients’ concerned others, and treatment providers. Methodology: The Reach, Effectiveness, Adoption, Implementation, and Maintenance—RE-AIM—framework will guide our study. Aim 1: VHA patients with non-fatal overdoses will be identified using Corporate Data Warehouse (CDW), Commun...