Objective: To improve success rates in psychotherapy, we developed and evaluated an alliance-focused training (AFT) protocol with regard to patient–therapist interpersonal behavior in a 30-session protocol of cognitive-behavioral therapy (CBT) for outpatients comorbid with Axis I and II conditions. Method: Participants included 40 patients treated by 40 therapists in a multiple baseline design in which novice therapists trained to fidelity standards in CBT were introduced to AFT at different time intervals (after either 8 or 16 sessions) during a 30-session CBT protocol. Interpersonal behaviors were assessed with a simplified version of the Structural Analysis of Social Behavior (SASB) on videotaped sessions sampled from the early (between Sessions 6 through 8), mid (Sessions 14 through 16), and late (Sessions 22 through 24) phases of therapy. Results: As predicted, several significant interactions were observed between within-subject interpersonal change and between-groups differences in exposure to AFT. Specifically, there were decreases in patient dependence and in therapist control (including criticism), plus increases in patient expressiveness and in therapist affirmation and expressiveness, all of which could be attributed to AFT. The predictive relationship of several of these variables to session-level and overall treatment outcome was also demonstrated. Conclusions: This study demonstrates that novice CBT therapists can be trained to improve their interpersonal process with patients who present with comorbid diagnoses, including a personality disorder.