Training in supervisory competencies is essential to effective clinical practice and helps address the current national crisis in the behavioral health workforce. Interactional supervision, the approach used in the current study, is well established in clinical social work and focuses the task of the supervisee on the interpersonal exchanges encountered in clinical practice. This study examines the feasibility of supervisory competency training and associated gains in competencies among 81 clinical supervisors. Three types of competencies are assessed before and after training and at a 3-month follow-up--managing supervisory relationships, managing job performance, and promoting professional development. The results show that competency training is a feasible and potentially effective approach and is associated with supervisor satisfaction and stress management. The training employed is compatible with skills-based and intervention-specific supervisor training common among evidence-based treatments and is appropriate for use with clinical social workers, counseling and clinical psychologists, and psychiatric nurses. (Contains 6 tables.)