This handbook comprehensively reflects, presents and summarises both first and second wave scholarship into Policy Advisory Systems (PAS). Bringing together leading scholars to engage persistent as well as emergent themes, the handbook provides a single volume highlighting both classic and new directions for PAS research, summarising both existing knowledge and outlining possible future findings. Covering the activities of a range of advisory system members from think tanks to public services, this handbook examines a broad set of administrative traditions and institutions affecting such systems in democratic, developing, authoritarian political regimes, and in supranational and transnational governance arrangements. It focusses on the systematic interactions of the supply, demand and brokerage of policy advice in different jurisdictions, and shows how these systems operate and evolve. The Routledge Handbook of Policy Advisory Systems is essential reading and an authoritative reference for scholars, students, researchers and practitioners of public policy, public administration, and public management. Those interested in comparative politics and government, international and public organisations and the use, influence and impact of policy advisory systems in a range of policy domains will find its comprehensive scope and coverage of great benefit.