Global developments over the past half-century have transformed public administration and brought it to maturity as an autonomous discipline at the intersection of many important fields of study. The trends and challenges which confront this discipline are analyzed in this festschrift, which honors Gerald E. Caiden and his numerous inputs to the field since his graduation in 1957. During five decades of research and teaching, Dr Caiden's professional life has spread across four continents, contributing greatly to the development of scholars and professional practitioners throughout the world. Their advancement of our knowledge of the public sphere worldwide and support of enhanced practices, combined with Caiden's scholarship, continue to define vital aspects of contemporary public administration and its future prospects, both locally and globally. The administrative state, which peaked in the 1950s and 1960s, gave way to neoliberalism and the new public management during the 1980s and 1990s. Already this is changing, as new ideas and visions surface on the horizon. Likewise, priorities shifted, as this volume shows.Concerns with central planning, with control, command and direction, gave way to greater emphasis on decentralization, de-bureaucratization and human resources development but also, lately, ethics and anti-corruption strategies. Due process, rule of law and defense against arbitrariness; protection and promotion of human and citizens' rights have also re-emerged as fields of growing concern, precisely on account of government's visible deficit in these regards. We are constantly on the move, but whether our direction will lead to the 'garrison state' or to a democratic 'facilitative state', as one contributor argues, remains a central issue, which calls for exploration and debate. In paying Gerald Caiden the tribute he so richly deserves, this festschrift, put together by scholars from around the world, traces and accounts for developments and bring us up to date. It is a fifty-year perspective on a field in rapid change; a rich and varied compendium, which represents a valuable addition to the literature on public administration, a necessary tool for training and research, as well as a useful companion for students and practitioners of public service globally.