This study tests the effectiveness of Making Alcoholics Anonymous Easier (MAAEZ), a manual-guided intervention designed to help alcohol and drug dependent clients connect with individuals encountered in AA. An OFF/ON design was used (n=508). MAAEZ effectiveness was determined by comparing abstinence rates of participants recruited during ON (MAAEZ intervention) and OFF (usual care) conditions and by studying the effect of the number of MAAEZ sessions attended. Better outcomes were hypothesized for MAAEZ vs. usual care. At 12 months, more clients in the ON condition (vs. OFF) reported past 30-day abstinence from alcohol, drugs, and both alcohol and drugs. Abstinence increased for each additional MAAEZ session received. MAAEZ appeared especially effective for those with more prior AA exposure, severe psychiatric problems, and atheists/agnostics. Mechanisms of action for MAAEZ (mediators of the MAAEZ effect) include: doing service in AA/NA/CA; having a sponsor; having a social network supportive of abstinence; and comfort being in meetings. MAAEZ represents an evidence-based intervention that is easily implemented in existing treatment programs.