This editorial introduction presents an overview of the themes explored in the symposium on ‘Deliberative Systems in Theory and Practice’. The concept of ‘deliberative system’ has gained renewed attention among deliberative democrats. A systemic approach to deliberative democracy opens up a new way of thinking about public deliberation. However, as the key protagonists responsible for the systemic resurgence acknowledge, the framework requires greater theoretical critical scrutiny and empirical investigation. The symposium will contribute to this endeavor by bringing together cutting edge research on the theory and practice of deliberative systems. This introduction offers a brief outline and review of the existing systemic approaches to deliberation, articulating the overlaps and differences and reflecting on the prospects and problems of each. In doing so, we take a generational approach that delineates the development of deliberative democracy into three generations, and argue that the focus on deliberative systems has implications that are so significant for the examination of theory and practice that it heralds a fourth generation for deliberative democracy. We conclude this introduction by providing a brief synopsis of each paper and highlighting the significance of the debates for critical policy studies.