This report provides a rapid review of evidence on the potential cost savings associated with providing screening, brief intervention, and referral to treatment for individuals with substance use disorders (SUDs) related to alcohol and drug use in emergency departments (EDs). Over approximately two weeks, the research team synthesized available peer-reviewed evidence using a comprehensive search strategy of literature published after 2010, deeming eight eligible studies for inclusion. Taken as a whole, the eight studies suggest that these programs can be cost effective, although cost-related findings appear to be sensitive to factors, including the type of clinical worker performing each task and patient characteristics. More rigorous evaluation is needed, particularly of new programs that include initiation of evidence-based SUD treatment in the ED.