We investigated changes over 12 to 42 months in 23 predoctoral trainees during their externship training in a psychodynamic/interpersonal psychotherapy clinic. Over time, trainees increased in client-rated working alliance and real relationship, therapist-rated working alliance, client-rated interpersonal functioning, ability to use helping skills (e.g., challenges, immediacy), higher-order functioning (e.g., conceptualization ability, countertransference management), feelings about themselves as therapists (e.g., more authentic, more self-aware), and understanding about being a therapist (e.g., theoretical orientation, curiosity about client dynamics). In contrast, trainees did not change in engaging clients (return after intake or for at least 8 sessions), judge-rated psychodynamic techniques in third and ninth sessions across clients (although trainees used more cognitive–behavioral techniques over time in third but not ninth sessions), or changes in client-rated symptomatology. Trainees primarily attributed changes to graduate training, individual and group supervision, research participation, and working with clients. Implications for training and research are discussed.