This study examined therapists' fidelity to a manualized, multicomponent cognitive-behavioral intervention for posttraumatic stress disorder (PTSD), including exposure therapy, among public sector patients with a psychotic disorder. Independent raters assessed therapists' competence and adherence, rating 20% of randomly selected audio taped sessions (n=57 sessions, coded by two raters, with strong interrater agreement). Adherence ratings indicated that therapists complied well with the protocol, and competency ratings typically averaged "very good" or higher (6 on 7-point Likert scale). Findings suggest that therapists can effectively deliver a manualized cognitive-behavioral intervention for PTSD, with exposure therapy, to patients with severe mental illness without compromise to the structure of sessions and/or the therapeutic relationship.