Approaches incorporating 12-Step beliefs and practices have dominated substance abuse treatment despite a lack of empirical support. Recent claims for effectiveness relying on results from a large, multisite research project in the U.S. were re-evaluated based on critical analysis of design, methodology, and construction of outcome measures. Contrary to claims, experimental design did not allow comparison of effectiveness of 12-Step versus cognitive-behavioral interventions but does allow evaluation of outcome measures for a single treatment intervention infused with 12-Step beliefs and teachings. Corrected for design and methodological errors, results support estimated "remission" rates for alcohol abuse of at most 15-20% and for substance abuse of 0-15%. Elements inherent in 12-Step practices and beliefs, including step work, run counter to accepted counseling and therapeutic factors believed to predict positive outcomes. Lack of effectiveness or outcomes less beneficial than no treatment are thus not unexpected for courses of treatment infused with 12-Step elements.