Objective: This study was an investigation of the relationships among therapist training variables, psychotherapy process, and session outcome in a psychotherapy training clinic. The aims were to assess the relationship between "training as usual" and intervention use in individual psychotherapy, to investigate the relationship between therapist intervention use and session outcome, and to test whether training variables moderate this relationship. Method: Graduate student therapists (n = 19; mean age = 27 years; 79% women; 84% White) provided information about their training and completed a measure of intervention use (Multitheoretical List of Therapeutic Interventions; McCarthy & Barber, 2009) and clients (n = 42; mean age = 33 years; 64% women; 95% White) completed a measure of session outcome (Session Progress Scale; Kolden, 1991) after each session of individual psychotherapy. Results: With regard to intervention use and session outcome, no main effects were found for the training variables. Consequently, tests of moderation were not performed. The final model for intervention use and session outcome yielded main effects for time-varying interpersonal therapy and time-varying common factor use, and a 3-way interaction among time-varying cognitive-behavioral (CBT) intervention use, between-patient common factor use, and between-therapist common factor use. Patients who received more common factor interventions on average rated sessions as less helpful when more CBT interventions were employed; this finding was stronger for patients who were being treated by therapists with higher average levels of common factor use. Conclusions: Implications for training are discussed, with particular attention paid to the importance of clinical decision making and the complex interaction between common and unique technical factors in practice. (Contains 3 tables, 1 figure and 5 footnotes.)