Deliberate practice (DP) is recommended as a new approach to facilitate the acquisition of discrete therapeutic skills, however, its implementation and effectiveness in psychotherapy remains unclear. A systematic search on DP for therapeutic skills among psychotherapy trainees and psychotherapists yielded eleven studies for inclusion. Nine were randomized controlled studies (RCTs), including seven unique RCTs, and two were within-group studies. Risk of bias was assessed as "high" for one RCT, "some concerns" for the remaining RCTs, and "serious" for within-group studies. All RCTs found the DP group performed better than the control group. All studies involved efforts to improve performance based on learning objectives and iterative practice but varied in the source of expert guidance and feedback. The included studies provide limited insight into best practice for delivering DP. The results highlight the paucity of research in this field; however they offer insight into current applications of DP and provide preliminary empirical support DP for as a model for promoting the development of discrete therapeutic skills. Given the rapid dissemination of DP publications and manuals in psychotherapy, future research is strongly encouraged.