This article investigates whether patients' sense of self and therapists' interventions aimed at orienting patients toward affect produce an affective activation in the patient. Both the independent contribution of sense of self and therapist intervention, as well as sense of self's moderating effect on therapist interventions, were investigated. Fifty cluster C patients were analyzed using 2 psychotherapy process measures and multilevel modeling. The results indicate that patients' affect experience increases over time. Both the therapist orienting the patient toward affect and the patient's sense of self predicted affect activation for the within-person effect (i.e., the patient's or therapist's standing in any given session relative to his or her baseline), but only sense of self was significant for the between-person effect (i.e., the patient's standing relative to all other patients). The relationship between a therapist orienting the patient toward affect and the patient's affective response was moderated by the patient's sense of self. The results have implications for therapists who want their patients to experience affect in a session.