An evaluation of the available outcome studies using personal construct therapy is much needed. This evaluation begins with a brief account of some of the major assumptions and practices of the therapy. A description of the 19 studies includes type of therapy, country of origin, type of client, client age, client sample size focus of the outcome data, type of analysis, and whether the outcome was favorable. The evaluation of the studies deals with these aspects of the research: sampling, design, measures of the dependent variables, analyses, and treatment validation. Effect sizes for nine of the studies are calculated and examined. There are also seven important issues that need to be considered in evaluating this research. Finally, given the evidence from a number of sound studies, I endorse the use of this therapy and suggest that further rigorous studies be conducted on the impact of personal construct therapy.