OBJECTIVES: Emergency medical services (EMS) post-overdose outreach programs expand beyond traditional 9-1-1 response to offer overdose survivors linkage to substance use treatment and other related harm-reducing interventions. Although intuitive and increasingly popular, evidence to define expected outcomes is exceedingly limited. We evaluated process and patient outcomes of one large Midwestern post-overdose outreach program to describe outreach characteristics and linkage to substance use treatment. METHODS: This retrospective cohort study used clinical program records of individuals referred to a multidisciplinary post-overdose outreach program following a non-fatal presumed opioid overdose with emergency response. Measures included (i) number of outreach attempts, (ii) modalities of outreach attempts (in-person visit, text message, letter, phone call, or electronic mail), (iii) outcome of outreach (i.e., if the individual was contacted), (iv) interventions provided including linkage to substance use treatment with coordinated admission and transportation. We used descriptive statistics to report patient characteristics, outreach frequency, outreach modality, successful contact, and treatment linkage through the program. RESULTS: From 2020 to 2022, the program attempted outreach to 3,437 individuals. The median age was 37 years (interquartile range, IQR, 30-47). Most individuals were white/non-Hispanic ( CONCLUSIONS: Post-overdose outreach initiated by EMS can successfully find and link individuals to substance use treatment following a non-fatal opioid overdose. However, this intervention may be resource intensive, often requiring multiple attempts at outreach and several modalities of interaction to facilitate treatment linkage.