Anne Alonso was passionate about the practice of supervision. An excellent supervisor herself, she sought to identify and teach the ingredients of effective supervision throughout her career. Her first book, The Quiet Profession (1985), was about the supervisory relationship and the various influences on it from within and without the relationship, and she insisted that the Center for Psychoanalytic Studies training program that she directed for many years include a required course on supervision. While the usual focus in supervision is on the supervisee and the clinical material presented, supervisors often experience powerful emotional reactions. Sometimes this is parallel process, in which the dynamics of the psychotherapy are replayed in the supervisory relationship. However, many other sources can contribute to supervisory affect, including the personality, background, and developmental stage of the supervisor, the impact of the clinical material, and the setting in which the supervision takes place. Supervisory reactions can be informative about the psychotherapy being supervised, about the supervisory relationship, or about the supervisor. Supervisors need self-awareness in order to identify their own contribution to their affective responses in supervision. The use of a supervisor decision tree of 1) awareness of reaction, 2) identification of its source, 3) relevance to current supervision, and 4) appropriate use of the reaction in the current supervision is recommended.