Context: In response to the drug overdose crisis, first responders, in partnership with public health, provide new pathways to substance use disorder (SUD) treatment and other services for individuals they encounter in their day-to-day work. Objective: This scoping review synthesizes available evidence on first responder programs that take an assertive approach to making linkages to care. Results: Seven databases were searched for studies published in English in peer-reviewed journals between January 2000 and December 2019. Additional articles were identified through reference-checking and subject matter experts. Studies were selected for inclusion if they sufficiently described interventions that (1) focus on adults who use drugs; (2) are in the United States; (3) involve police, fire, or emergency medical services; and (4) assertively link individuals to SUD treatment. Twenty-two studies met inclusion criteria and described 34 unique programs, implementation barriers and facilitators, assertive linkage strategies, and linkage outcomes, including unintended consequences. Conclusions: Findings highlight the range of linkage strategies concurrently implemented and areas for improving practice and research, such as the need for more linkages to evidence-based strategies, namely, medications for opioid use disorder, harm reduction, and wraparound services.