This National Institutes of Health funded study investigated spiritual growth as a change mechanism in 12-step programs. A total of 130 people, early 12-step affiliates with limited Alcoholics Anonymous (AA) histories, were recruited from 2007 to 2008 from AA, treatment, and community centers in a Southwestern city in the United States. A majority of the sample was alcohol dependent. Participants were interviewed at baseline and at 3, 6, and 9 months. Lagged General Linear Modeling analyses indicated that spiritual change as measured by the Religious Background and Behavior (RBB) self-report questionnaire were predictive of increased abstinence and decreased drinking intensity, and that the magnitude of this effect varied across different RBB scoring algorithms. Future research should address study limitations by recruiting participants with more extensive AA histories and by including assessments of commitment to, and practice of, AA prescribed activities. The study's limitations are noted.