People seeking help for their alcohol or other drug problems enter treatment with very different levels of motivation to change. Differences in motivation appear to make a critical difference in which patients seek, comply with, and complete treatment. Findings from a study of the extent to which motivation and self-efficacy — the confidence to resist temptation and to abstain from drinking — changed during treatment, and the degree to which these variables affected drinking behaviors, indicate that treatments tailored to specific subgroups may be more effective.