This article examines the critical factors and outcomes of coproduction in public service delivery. Three research questions are posed: What is the role of citizens in coproduction? What are the critical factors of coproduction? What are the outcomes of coproduction? The study aims to contribute to a deeper understanding of the impact of coproduction by undertaking a systematic review. Traditional academic reviews are departed by examining policy and practice evidence that is drawn from 56 worldwide cases. Outcomes are identified that mainly concern the enhanced capacity of both organizations and individual participants, improved effectiveness of services, increased citizen engagement and citizen satisfaction. Evaluation of our review evidence is used to articulating a coproduction model that can inform theoretical developments in advancing coproduction research. In summary, it is suggested that coproduction can be a viable strategy in public services depending on the conditions and circumstances of the context. Implications and future research agenda are provided in conclusion.