A sample of 301 clients from a large substance abuse treatment facility was surveyed utilizing a pretest/posttest design. Participants completed measures both prior to participating in outpatient treatment and then approximately 7 months after discharge. Twelve-step participation was measured, along with effects of the individual 12 steps, to determine any contribution to treatment outcomes, including spirituality, health, mental health, and alcohol and other drug (AOD) outcomes. Analyses were conducted to determine if participation changed over the study period and whether it impacted outcomes after treatment. Results indicated that participation and the effects of the individual steps were not statistically significant in relation to many treatment outcomes. However, these factors were important in the development of client spirituality.