Objective To compare the effectiveness of social behaviour and network therapy, a new treatment for alcohol problems, with that of the proved motivational enhancement therapy. Design Pragmatic randomised trial Setting Seven treatment sites around Birmingham, Cardiff, and Leeds. Participants. 742 clients with alcohol problems; 689 (93.0%) were interviewed at three months and 617 (83.2%) at 12 months. Interventions Social behaviour and network therapy and motivational enhancement therapy. Main outcome measures Changes in alcohol consumption, alcohol dependence, and alcohol related problems over 12 months. Results Both groups reported substantial reductions in alcohol consumption, dependence, and problems, and better mental health related quality of life over 12 months. Between groups we found only one significant difference in outcome, probably due to chance: the social network group showed significantly better physical health at three months. Non-significant differences at 12 months in the motivational group relative to the social network group included: the number of drinks consumed per drinking day had decreased by an extra 1.1 (95% confidence interval −1.0 to 3.2); scores on the Leeds dependence questionnaire had improved by an extra 0.6 (−0.7 to 2.0); scores on the alcohol problems questionnaire had improved by an extra 0.5 (−0.4 to 1.4); but the number of days abstinent from drinking had increased by 1.2% less (−4.5% to 6.9%). Conclusion The novel social behaviour and network therapy for alcohol problems did not differ significantly in effectiveness from the proved motivational enhancement therapy.