Congressional politics of the past decade have shown the power of intraparty organizations on Capitol Hill. Be it the House Freedom Caucus’s efforts to topple Speaker John Boehner (R-OH) or the Blue Dogs’ successes shaping the Affordable Care Act, the actions of party factions have been on prominent display during many major legislative efforts in recent years. Yet scholars have paid surprisingly little attention to intraparty organizations in Congress, and we know little about how these factions form or how they influence the individual and collective actions of lawmakers. Ruth Bloch Rubin’s Building the Bloc is an excellent exception, demonstrating the pivotal importance of these organized factions, and the crucial organizational work that paves the way for their influence.

The book’s central argument is that “intraparty organization is often the key to transforming lawmakers’ potentially pivotal votes into the policy outcomes they desire, particularly when those outcomes are at odds with the interests of party leaders” (p. 13). By forming organized alliances, factions of lawmakers can develop institutional arrangements that reinforce their members’ commitments to work together to achieve common goals, often those opposed by the rest of their party. While specific institutional arrangements and structures vary from faction to faction, and between House and Senate factions, Bloch Rubin finds that successful intraparty groups are able to “ameliorate division and disorder among party dissidents in three important ways” (p. 14).

First, these organized factions provide participating members with select incentives that reward their investment in and commitment to achieving the collective goals of the group. These incentives vary but can include electoral benefits, such as direct campaign support or access to a factional brand name (like “Blue Dogs”) that can provide meaningful signals to a lawmaker’s constituents. It can also include institutional benefits, including access to party leaders, opportunities at valuable committee seats, and more.

Second, these intraparty organizations allow members to convert the public goods they desire—typically a public policy—into partially excludable accomplishments for which they can claim the most credit. By joining the faction, its members can take the efforts and accomplishments of the group back home to their voters and tout their involvement. Third, intraparty factions provide members a forum to debate, deliberate, and reach consensus about the substance of the policies they will support. Building internal unity in this way subsequently helps increase a group’s bargaining power with party leaders in the House and Senate.

The bulk of the chapters take deep dives into the emergence and activities of some of the most notable intraparty factions of the twentieth and twenty-first centuries. These include the progressive Republican factions that toppled Speaker Joseph Cannon (R-IL) and pushed for economic reforms in the House and Senate in the first decade of the twentieth century (Chapters 2 and 3); the Southern Democratic organizations of the 1930–60s and their efforts to oppose Civil Rights reform (Chapters 4 and 5); the Blue Dog Democrats from their emergence in the 1990s to their efforts to influence the Affordable Care Act in 2009–10 (Chapter 6); the liberal Democratic Study Group that emerged to counter conservative Southern Democrats in the 1950s and went on to play a central role in reforming Congress in the 1970s (Chapter 7); and conservative Republican factions from the emergence of the Republican Study Committee to today’s House Freedom Caucus with their efforts to move the Republican Party to the right (Chapter 8). The breadth and depth of these historical and contemporary case studies are truly impressive, providing nuance and detail that bring to life and contextualize the central role intraparty organizations have played in some of the most consequential legislative battles of the past 110 years.

Bloch Rubin marshals tens of thousands of pages of archival evidence, combined with interviews with contemporary party faction members, to explore how her theory explains the behaviors, successes, and failures of intraparty organizations. Building the Bloc shows the value of these methodological approaches. Indeed, the book’s findings likely could not have been produced without these historical and qualitative methods. Studies relying solely on quantitative measures of legislative behavior miss the crucial work that goes into the organizing of party factions, and the role that those organizational institutions play in shaping the congressional politics we observe.

Take, for instance, one of the most important findings uncovered in this work—the role that intraparty organizations play in shaping the preferences of their members, or as Bloch Rubin puts it, “the collective origins of individual preferences” (p. 301). Studies of Congress frequently treat legislators’ policy positions as exogenously determined “preferences,” measured using ideal point estimates that are individualistic to the member at hand. Such a preference-based understanding of congressional politics implies that intraparty factions will form simply because members have tightly aligned preferences and so will naturally work in unison to achieve them. The book demonstrates that reality is far more dynamic and uncertain. Members may seek to form an organized intraparty faction out of common goals or interests, but translating those goals into specific issue positions and actions takes work—consideration, deliberation, and debate among a group’s members, combined with institutional rules, incentives, and sanctions that keep group members in line once policy positions are established.

Bloch Rubin shows this best in the chapter on the Southern Democratic Caucus and its efforts to fight against Civil Rights reform. Scholarly understanding of the Southern Caucus typically portrays southern white senators as naturally in step on “southern” issues. But this misses the important role that the caucus played in forming the specific policy positions its members united behind. For Southern Democrats or any other intraparty faction, work is required to identify and construct the policy positions that form an “ideology,” or a programmatic agenda in the halls of Congress. In other words, someone has to decide “what goes with what,” as Phillip Converse put it, create “ideological coherence,” and shape what it means to be a “Southern Democrat.” Bloch Rubin’s careful analysis provides strong evidence that the “preferences” we measure are not exogenously determined, but rather meaningfully shaped by the strategic actions of lawmakers in office, which in turn meaningfully shape congressional action as it unfolds.

Important implications such as these abound in this book. If anything, I wish it had gone even farther in considering the inferences that can be drawn from some of these findings. In shaping the positions of a faction of a party, can intraparty organizations ultimately shape the positions adopted by the party at large? If they can shape what it means to be a moderate or a conservative or a progressive within a party, can they also ultimately shape what it means to be a Democrat or Republican in the long run? Answers to questions like these could provide tremendous insight into congressional politics and the evolution of our political parties.

Building the Bloc is an excellent book and one that should be read by students of Congress, political parties, and American political history. Its findings and implications should be closely considered by scholars as we study the congressional politics of the past and present.