Beginning in the 1920s, Freudian psychoanalytic theory had a deep impact on social work practice and education and helped to professionalize clinical social work. Not as well-known was the role that Freud's patient and colleague Sándor Ferenczi played in this evolution. Through a review of the relevant literature and primary sources—some presented here for the first time—I will explore the ways in which Ferenczi's work directly impacted the development of clinical social work.