Comparative public administration (CPA) is directed at the study of administrative phenomena focusing on organization (bureaucracy), personnel (public employees, administrative elites), and the relations between administrative actors/processes and political decision makers (making). The comparative approach encompasses cross-sectional (e.g., cross-country and cross-policy) as well as cross-time (longitudinal) analyses. In its historical development CPA research unfolded in the United States after 1945 in focusing on developing countries. Since the 1970s CPA research has largely turned on “developed” industrial countries in increasingly dealing with European (particularly EU member) as well as other Organisation for Economic Co-operation and Development (OECD) countries. With regard to subject matter, the study of organization and personnel, as well as the relations between administrative actors and political decision makers, have loomed large. As occurred in the wake of the marketization and privatization of public functions prompted by New Public Management, the distinction between public and private has blurred the “radar” of CPA researchers and has accordingly widened. The growth of CPA research has been reflected in and promoted by the proliferation of CPA-related national and international professional and academic associations, networks, journals, publications (handbooks, textbooks, etc.), and databases. While the appropriate (“purposive”) selection of countries (and cases) is of key importance in the conduct of valid comparative research, it often proves impossible to apply methodologically rigorous (“quasi-experimental”) comparative logic, so that most research has settled for methodologically softer selection strategies. While in the past qualitative (case-study based) research has prevailed, recently quantitative-statistical analyses have advanced. In sum, the state of art in CPA research offers a mixed balance. On the one hand, there seems so far to be no generally accepted single theory or methodological approach in the pursuit of CPA research. On the other hand, the large (and still growing) body of CPA research findings (and the steady accumulation of research experience and sophistication in the research community) hold the promise of further advances, including theory-building.