A number of studies have linked the development of substance abuse problems to a lack of purpose or meaning in life, and a few studies have demonstrated an increase in sense of life purpose through substance abuse treatment programmes. The present study extended past research by examining the relationship of purpose in life to treatment outcome assessed three months after completion of treatment. The subject sample comprised 131 people in in-patient treatment programmes or awaiting treatment for alcoholism (in some cases in addition to other drug addictions). Consistent with previous research, the mean Purpose in Life Test (PIL) score before treatment was significantly below the normal range and the mean PIL score at the end of in-patient treatment was within the normal range. Furthermore, the PIL score at the end of treatment was predictive of changes in intimate relationships and health at follow-up. It was also predictive of follow-up drinking/drug use status. However, the pattern of prediction differed in the two treatment groups. Post-treatment PIL score was a positive predictor of improvement in a skill-based treatment centre, and a negative predictor in a more authoritarian, confrontation-based programme. The distinction between internally and externally derived senses of meaning is presented as one possible explanation of these findings.