The current study investigated how clients' perceptual processing changes over the course of therapy and how clients' perceptual processing at the late stage of therapy relates to outcome by comparing two types of therapy for depression, cognitive behavioural therapy (CBT) and process-experiential therapy (PET). Data was drawn from the Watson, Gordon, Stermac, Kalogerakos & Steckley (2003) archival database, wherein sixty six clients were diagnosed with major depression and received 16 weeks of treatment; 33 clients received CBT and 33 clients received PET. Three sessions for each client were selected, one from the early, middle, and late stages of therapy. Selection was based on clients' highest rating on the Client Task Specific Change Measure - Revised. The middle twenty minutes of each selected session were rated on the Levels of Client Perceptual Processing measure (LCPP; Toukmanian, 1986, 1992; Toukmanian & Gordon, 2004). Clients' perceptual processing levels were examined over the course of therapy (three stages) and in relation to depressive symptoms, self-esteem, dysfunctional attitudes, interpersonal problems, general symptom distress, and problem-focused coping at posttreatment and follow-up. Results indicated that clients in both therapies became more reevaluative and integrated new perspectives over the course of therapy. Clients in CBT engaged in more differentiation with analytic focus to make meaning of their experiences than clients in PET while clients in PET engaged in more differentiation with internal focus to make meaning of their experiences than clients in CBT. Clients' use of reevaluative statements at the late stage of therapy was related to a decrease of depressive symptoms, dysfunctional attitudes, interpersonal problems, general distress, suppressive coping, and reactive coping, and to an increase in self-esteem, at posttreatment and at follow-up for clients in CBT and for clients in PET. Clients' use of integrative statements at the late stage of therapy was related to a decrease in dysfunctional attitudes, suppressive and reactive coping, and to an increase in reflective coping at posttreatment and at follow-up for clients in CBT and for clients in PET. Implications for clinical work and future research are discussed.