Depression is one of the major contributors to poorer quality of life amongst individuals with psychosis and schizophrenia. The study was designed as a Pilot Trial to determine the parameters of a larger, definitive pragmatic multi-centre randomised controlled trial of Acceptance and Commitment Therapy for depression after psychosis (ACTdp) for individuals with a diagnosis of schizophrenia who also meet diagnostic criteria for major depression.Participants were required to meet criteria for schizophrenia and major depression. Blinded follow-ups were undertaken at 5-months (end of treatment) and at 10-months (5-months posttreatment). Primary outcomes were depression as measured by the Calgary Depression Scale for Schizophrenia (CDSS) and the Beck Depression Inventory (BDI).A total of 29 participants were randomised to ACTdp + Standard Care (SC) (n=15) or SC alone (n=14). We did not observe significant differences between groups on the CDSS total score at 5-months (Coeff=−1.43, 95%CI −5.17, 2.32, p=0.45) or at 10-months (Coeff=1.8, 95%CI −2.10, 5.69, p=0.36). In terms of BDI, we noted a statistically significant effect in favour of ACTdp+SC at 5-months (Coeff=−8.38, 95%CI −15.49, −1.27, p=0.02) but not at 10-months (Coeff=−4.85, 95%CI −12.10, 2.39, p=0.18). We also observed significant effects on psychological flexibility at 5-months (Coeff=−8.83, 95%CI −14.94, −2.71, p<0.01) but not 10-months (Coeff=−4.92, 95%CI −11.09, 1.25, p=0.11).In this first RCT of a psychological therapy with depression as the primary outcome, ACT is a promising intervention for depression in the context of psychosis. A further large-scale definitive randomised controlled trial is required to determine effectiveness.Trial registration: ISRCTN: 33306437