Background <p>Cognitive Behavioral Social Skills Training (CBSST) is a targeted psychological intervention designed to improve daily functioning and to address negative symptoms in individuals diagnosed with schizophrenia. Despite evidence from clinical trials suggesting beneficial effects of CBSST on functioning and negative symptoms, the overall efficacy of CBSST remains to be quantified. Furthermore, potential moderators and mediators of treatment outcomes remain elusive. This protocol outlines an individual participant data meta-analysis (IPD-MA) with the objective to examine the efficacy of CBSST on psychosocial functioning in schizophrenia.</p> Method <p>In accordance with the Preferred Reporting Items for a Systematic review and Meta-Analysis of Individual Participant Data (PRISMA-IPD) guidelines, we will conduct a systematic literature search and employ two-stage and one-stage meta-analytical approaches. The meta-analytical models will evaluate the overall effect of CBSST relative to control treatments in randomized-control trials, identify participant-level (e.g., age, cognitive impairment) and study-level (e.g., individual vs. group settings) predictors of change, and explore the mechanisms that mediate improvement in functioning, such as skills acquisition and cognitive restructuring of defeatist attitudes. Furthermore, the analysis will attempt to determine the optimal amount of CBSST sessions required to enhance functioning and evaluate the impact of patient-level factors driving delivered dosage.</p> Discussion <p>The objective of this study is to contribute to the existing literature by addressing the current gaps in understanding the efficacy of CBSST and identifying critical factors for treatment success. Our findings will have the potential to inform personalized treatment planning and the development of clinical guideline recommendations focusing on functional outcomes and negative symptoms in people with schizophrenia.</p> Systematic review registration <p>PROSPERO CRD42024605353.</p>