The last 10 years have shown a notable increase in the consideration of locus of control as a variable pertinent to the explanation of outcome in psychotherapy. In particular, a body of research has provided evidence that an internal locus of control orientation facilitates both positive assessments of therapy and favourable outcomes, and that successful outcomes for clients with particular control orientations are facilitated by the degree of structure and directiveness in therapy. There appear to be a number of difficulties with the methods of measurement employed in these studies; in particular, the selection of subject groups and indexes of outcome as well as manipulation of treatment structures may have limited the generalizability of research findings. The possible therapeutic and clinical applications of locus of control in psychotherapy are considered.