There is a relatively large body of literature on how psychotherapy education should be taught and learned. Less attention has been directed towards how therapists learn. The aim of the present literature review is to consider research published from 2000 until present concerning learning processes in psychotherapy and supervision. The main questions were: What is the scope and quality of available research and what is considered known and unknown concerning how therapists learn to become psychotherapists. Search and selection criteria were developed and tested for reliability. Subsequent searches were performed using the Proquest multi database platform. An analysis of findings generated so far suggests a continued lack of research on how psychotherapists learn their trade. Implications of this finding are further discussed.