Research on the nature and bases of the political alignments of the middle class in the United States has produced extensive disagreements but little resolution of fundamental controversies. We address unresolved questions about the political alignments of the middle class through an investigation of change in voting behavior among two of its principal segments: managers and professionals. Among professionals, but not among managers, there has been a long-term shift away from support for Republican presidential candidates to support for Democratic candidates. Competing hypotheses about the sources of these trends are rested using data from the National Election Studies. Increasingly liberal attitudes reward social issues, not changes in economic evaluations or sociodemographic composition, explain the growing tendency of professionals to vote Democratic and their increasing divergence from managers. Party identification and partisan affect substantially mediate the effects of social group membership, views of the welfare state, and attitudes towards social issues. The relevance of these findings to understanding the Democratic realignment of professionals and the stable Republican alignment of managers is discussed.
