Why do governments create semi-autonomous public organizations, called 'agencies'? How do agency types and their prevalence differ across countries and time? How are agencies controlled and held accountable? How autonomous are they? How have (post)-New Public Management ideas affected agencification policies in Europe and beyond? How do governments attempt to restore transparency and coordination in a fragmented agency landscape? And what can practitioners and policy makers learn from international experiences? This volume describes and compare how semi-autonomous agencies are created and governed in 29 countries and the EU. It leads practitioners and researchers through the crowded world of agencies, describing the agency landscape, history and drivers, autonomy and control, as well as recent developments. It offers a rich empirical overview for researchers interested in comparing agencies in different countries, and for practitioners interested in agency practices and experiences. Evidence-based lessons and recommendations are formulated to improve agencification policies in post-NPM times. This is the first volume to cover all aspects of agencies and the phenomenon of agencification and will be an essential reference tool for policy makers and researchers.