A new work on Congress by one of the most prominent scholars of American government in the past half century is a major event. In this book, Nelson Polsby revisits the U.S. House, a subject on which he authored two major articles in the late 1960s (“The Institutionalization of the U.S. House of Representatives,” American Political Science Review 62 [March 1968]: 144–68; and Nelson W. Polsby, Miriam Gallaher, and Barry S. Rundquist, “The Growth of the Seniority System in the U.S. House of Representatives,” American Political Science Review 63 [September 1969]: 707–807). Observing the contemporary House in this volume, Polsby finds a chamber transformed. The “permanent” Democratic majority has been broken, the “solidly” Democratic South now sends a Republican majority to the House, committee chairs are subordinate to the party leadership, and levels of party voting are at their highest since the 1890s.

Polsby's work adds to a substantial scholarly literature on the transformation of the House, headed by David Rohde's Parties and Leaders in the Postreform House (1991) and Barbara Sinclair's Legislators, Leaders and Lawmaking (1994). In comparison with these works, Polsby's deals more with the technical, social, and electoral factors underlying congressional change. He sees electoral realignment in the South as critical, particularly the migration of northern Republicans after World War II that laid the basis for the emergence of a viable Republican Party in the southern states. Hence, Polsby's recurring theme: The invention of air-conditioning, which made the South more habitable to non-Southerners, ultimately proved crucial to change on Capitol Hill.

The book is divided into four substantive chapters, a shorter summary chapter, and a 20-page appendix on methods and sources. Here, Polsby sets out his “quasi-anthropological” approach, which, he argues, “attends to the ways in which the values and status systems of these [well-bounded] communities shape the fortunes of their members as well as the policies and strategies they pursue” (p. 156). (In so doing, he revisits his theory of “institutionalization,” a process by which a political body develops strong internal boundaries, becomes internally differentiated, and adopts its own peculiar rules and norms of behavior.) Polsby's method allows him to utilize an array of material that he has accumulated in 40 years of studying Congress, including personal observations; interviews; narrative accounts by members, journalists, and scholars; and ideological and voting data.

The first chapter summarizes the features of the House at the time of Speaker Sam Rayburn in the 1950s: weak party leadership, strong committee chairs, strict adherence to the seniority rule (which delivered crucial committee chairmanships disproportionately to southern conservative Democrats), and, despite the ostensible Democratic majority, ideological domination by a bipartisan “conservative coalition” of southern Democrats and Republicans. Chapter 2 illustrates the erosion of the conservative House regime in the 1960s and 1970s as the more junior, liberal members in the Democratic majority revived the party caucus and secured passage of reforms that eroded the seniority rule and the power of committee chairs, and further weakened the grip of the conservative coalition. Chapter 3 examines the electoral factors behind this liberalization, which Polsby views as primarily a consequence of the emergence of a viable Republican party in the South, engendered by in-migration and economic development. Gradual Republican gains in turn reduced the numbers of white southern conservatives in the House Democratic caucus and expedited the passage of reforms backed by the liberal Democratic Study Group.

Chapter 4 examines the consequences of these reforms. As the Democratic House majority became more homogeneously liberal, the power of the party leaders and levels of partisan voting and polarization rose, too. This, in turn, begat a furious reaction from the increasingly southern, and hence more conservative, Republican minority. When the Republicans took advantage of a number of short-term factors—an unexpectedly advantageous 1990 redistricting, Democratic retirements, congressional scandals, and the short-term unpopularity of President Clinton—to win control of the House in 1994, the new partisan House politics continued unabated. Chapter 5 summarizes what has gone before and elaborates the factors that determine congressional evolution according to Polsby: institutionalization, technology, sociopolitical movements, and innovations elsewhere in the political system.

How Congress Evolves is an intelligent, eminently readable, and accessible study that accurately summarizes how Congress has changed in the last half century and the reasons behind that change. The book also has the merit of reminding us that while it is an extraordinarily “well-bounded” legislature by contemporary standards, as a popularly elected body in a separated governmental system, Congress cannot be impervious to the wider social and political universe of which it is a part. Given the narrow institutional and methodological focus of much contemporary congressional research, this is entirely salutary. Readers may find Polsby's emphasis on the rise of the Republicans in the South as the fundamental explanation of congressional change somewhat overstated. Other contemporaneous changes in the electoral universe—the decline of machine politics, the rise of ideological and single-issue interest groups, political action committees closely affiliated with one or the other of the major parties, the rise of the news media, and the sharp decline in the number of electorally competitive districts—have surely also been instrumental in the emergence of the partisan, centralized House. Moreover, even within the southern context, Polsby somewhat underplays the importance of the 1965 Voting Rights Act in congressional realignment.

These caveats aside, Nelson Polsby has produced another valuable addition to his considerable corpus of scholarship on American government that will assist congressional experts, undergraduate and graduate students, and the politically aware general reader in understanding the contemporary Congress. The lesson that change in Congress can only be fully explained in the context of change in the wider American political universe may seem obvious, but it is one that American political science more than ever needs to learn today.