SOCIAL SCIENCE RESEARCH 19, 348-371 (I!?%)) Unions and the Structure of Earnings Inequality: Cross- National Patterns ARNE L. KALLEBERG Department of Sociology, University of North Carolina-Chapel Hill AND TOM COLBJQRNSEN Department of Organization Sciences, Norwegian School of Economics and Business Administration-Bergen and Norwegian Research Centre in Organization and Management We examine differences in the structure of earnings inequality for men in four advanced western industrialized nations that differ in the nature and extent of unionism: the United States, Canada, Norway, and Sweden. We argue that the economic effects of unionism depend on whether (I) the bargaining structures of labor markets are centralized or fragmented; and (2) the political organization can be characterized as a corporatist or a pressure-group system. We find some support for our principal hypotheses that cross-national differences in systems of collective bargaining and political institutions affect the size of the earnings gap between male union and nonunion members, as well as the extent of wage dispersion among unionized workers. (0 IWO Academic press. hc. Sociologists and economists are increasingly recognizing the need to study comparatively how social institutions segment labor markets. Com- parative research is necessary to understand how macroscopic forces- such as historical and cultural experiences of countries, or political econ- omies of nation states-shape earnings inequality and other features of labor market segmentation (see Kalleberg, 1988). For example, the degree of centralization in the union structure within a country influences the An earlier version of this paper was presented at the annual meetings of the American Sociological Association, Atlanta. 1988. This research was supported in part by National Science Foundation Grant SES-88-07196. For their valuable comments, we thank Aage B. Sorensen, Hans-Peter Blossfeld, and Alexander Hicks. Reprint requests should be ad- dressed to Arne L. Kalleberg, Department of Sociology, Hamilton Hall CB# 3210, Uni- versity of North Carolina. Chapel Hill, NC 27599. 348 0049-089X/90 $3.00 Copyright 0 IWO by Academic Press. Inc. All rights of reproduction iu any form raewed.