This paper reviews published randomized controlled treatment trials of psychological therapies added to standard psychiatric treatment vs. standard psychiatric treatment alone to explore whether adjunctive psychotherapy reduces relapse rates in individuals with bipolar disorders. Core components and characteristics of effective psychological therapies were identified from descriptions in the literature. Relapse rates were calculated for selected treatment trials and then pooled odds ratios were calculated using meta-analytical techniques that explored differences in outcome according to therapy model, type of relapse experienced and whether the subject was euthymic at entry to the study. The different therapy models have a number of similar components. A meta-analysis of eight recent studies demonstrates a significant reduction in relapse rates (of about 40%) compared to standard treatment alone. Therapies were most effective in preventing relapses in subjects who were euthymic when recruited into the treatment trial, and may be less effective in those with a high number of previous episodes (previous relapses >12). Efficacy studies demonstrate that adjunctive psychological treatments for individuals with bipolar disorders reduce relapse risk, but there is a need to undertake pragmatic effectiveness studies to determine which individuals with bipolar disorders are most likely to benefit from such interventions.