Aims: To evaluate relationships between clients' self-reported ‘stage of change’ and outcomes after treatment for alcohol problems. Methods: Using data from the ‘United Kingdom Alcohol Treatment Trial’, clients who had received at least one session of treatment and who had complete data (n = 392) entered the analysis. Two continuous measures of drinking behaviour (% days abstinent (PDA) and drinks per drinking day (DDD)) and categorical outcomes at the 12-month follow-up were compared between clients in Pre-action and Action stages of change at either pre- or post-treatment assessment. Multiple and logistic regression analyses examined the relationships between stage of change and treatment outcomes, evaluating the strength of these relationships by controlling for likely confounders. Results: Pre-treatment stage of change did not predict outcome but post-treatment stage of change predicted PDA and DDD at the 12-month follow-up. In unadjusted and adjusted analyses, clients in Action at post-treatment were two to three times more likely to show a favourable categorical outcome, variously defined, than those in Pre-action. There were no differences between clients who had received Motivational Enhancement Therapy and those who had received Social Behaviour and Network Therapy in proportions maintaining or moving towards Action from before to after treatment. Conclusions: These findings confirm previous reports that motivational variables predict outcome of treatment but add that such a relationship is seen for post-treatment stage of change. For therapists, it would seem important to monitor the client's stage of change—which in good clinical practice often occurs in informal ways—and have strategies to deal with low motivation to change whenever it occurs throughout treatment. The findings are also consistent with a ‘common factors’ perspective on effective treatment for alcohol problems.