- Citizens, Elections, Parties: Approaches to the Comparative Study of the Processes of Development, with Angus Campbell, Per Torsvik and Henry Valen, (Universitetsforlaget, 1970).
- Economy, Territory, Identity: Politics of West European Peripheries, with Derek W. Urwin, (Sage, 1983).
- Data Archives for the Social Sciences, (Mouton, 1966).
- Comparative Research across Cultures and Nations, (The Hague Mouton, 1968).
- Comparing Nations: the Use of Quantitative Data in Cross-national Research, co-edited with Richard L. Merritt, (Yale University Press, 1966).
- Party Systems and Voter Alignments: Cross-national Perspectives, co-edited with Seymour Martin Lipset, (Free Press, 1967).
- International Guide to Electoral Statistics, co-edited with Jean Meyriat, (Mouton, 1969).
- National Elections in Western Europe, co-edited with Jean Meyriat, (Mouton, 1969).
- Quantitative Ecological Analysis in the Social Sciences, co-edited with Mattei Dogan, (MIT Press, 1969).
- Social Ecology, co-edited with Mattei Dogan, (MIT Press, 1969).
- Mass Politics: Studies in Political Sociology, co-edited with Erik Allardt, (Free Press, 1970).
- Imagination and Precision in the Social Sciences: Essays in Memory of Peter Nettl, co-edited with T. J. Nossiter and A. H. Hanson, (Faber & Faber, 1972).
- Building States and Nations, co-edited with S. N. Eisenstadt, (Sage, 1973).
- Locational Approaches to Power and Conflict, co-edited with Kevin R. Cox and David R. Reynolds, (Sage, 1974).
- Sociological Praxis: Current Roles and Settings, co-edited with Elisabeth Crawford, (Sage, 1976).
- The Politics of Territorial Identity: Studies in European Regionalism, co-edited with Derek W. Urwin, (Sage, 1982).