Alcoholics Anonymous (AA) meeting attendance and spiritual practices are established predictors of abstinence. This study utilized longitudinal data from two studies of AA to investigate 1) how perceived within meeting social dynamics in AA meetings affect later AA attendance, and thus exposure to the emphasis of spiritual practices and 2) influence the extent that spiritual gains are mobilized, beyond AA attendance. Findings revealed that greater group cohesion was associated with lower AA attrition, and that expressiveness, or openness, of the group predicted reported practice of spiritual behaviors. Findings reveal distinct group dynamics may foster distinct mechanism of change of AA attendees.