A perusal of the published literature on psychotherapy reveals that what we know about psychotherapy is limited by the context in which the research is conducted and the priorities of the researchers with regards to questions, hypotheses, variables, and methods. In the past few decades, the emphasis in psychotherapy research has been investigating the efcacy of treatments using randomized controlled trials (Goldfried & Wolfe, 1998; Wampold, 2001). As well, increasingly counseling and psychotherapy process research has been conducted in the context of clinical trials; when such research is conducted in naturalistic settings, the sample sizes are relatively small and the variables studied are meant to explore theoretical aspects of therapy. As a result, we actually know relatively little about how psychotherapy is practiced in the real world. The purpose of this chapter is to review what we do know about the practice of psychotherapy.