Objective: This article reports the initial development of the Alcohol and Other Drug Self-Efficacy Scale (AODSES). Method: The scale instrument is designed to measure social workers' perceived self-efficacy of their substance abuse knowledge and skills with MSW practitioners (N =399). Results: Factor analysis revealed six subscale factors in the initial scale development com-posed of 43 items, accounting for 76% of the variance with excellent internal reliabilities. The six subgroup factors were moderately correlated. Conclusions: Given the reliability and validity of the scale, it may be useful in agency settings to evaluate and measure social workers' confidence in treating clients who have alcohol and other drug problems. Replication of the study is a necessary next step with another group of social workers for further external and internal validation.