Purpose of Review <p>This review examines <i>self-efficacy</i> and traces the construct from theory and operationalization to clinical practice and intervention design in addiction science.</p> Recent Findings <p>Self-efficacy is a construct with a strong theoretical and methodological foundation. While evidence for self-efficacy as a statistical mediator in the context of clinical trials of addictions treatments is mixed, it is most conclusive in within-condition, non-experimental designs. Consistency in empirical support across research methods, populations, and outcomes strengthens support for self-efficacy as a mechanism of alcohol or other substance consumption outcomes.</p> Summary <p>The current review provides evidence for self-efficacy as a mechanism worthy of direct attention in clinical care for alcohol or other substance use disorders. It is likely a common mechanism of human behavior change that can be harnessed in a range of treatment modalities and client-identified goals. Future work should target self-efficacy directly in intervention development, implementation, and dissemination.</p>