This study evaluated the effects of alcohol‐focused spouse involvement and behavioural couple therapy (BCT) on couple communication in the context of group drinking reduction treatment for male problem drinkers. Sixty‐four male clients and their female partners were randomly assigned to one of three conditions: (i) treatment for problem drinkers only (PDO), (ii) couple alcohol‐focused treatment or (iii) couple alcohol‐focused treatment combined with BCT. Couples whose partners participated in the treatment made fewer negative statements during a couple conflict communication task following treatment than PDO couples. The beneficial effect of spouse involvement on negative couple communication was partially mediated by a reduction in the frequency of clients’ heavy drinking during treatment. There was also evidence that BCT reduced couples’ negative communication and increased problem‐solving communication. Practitioner points Involving the spouse in group drinking reduction treatment for male problem drinkers can improve drinking outcome. Therapists can encourage spouses to decrease counterproductive behaviour and engage in behaviour supportive of drinking reduction. Actively involving the spouse can decrease negative statements during problem‐solving communications. Reduction in negative communication may be a result of, rather than a cause of, the male partner's drinking reduction.