David Redlawsk, Caroline Tolbert, and Todd Donovan have written an important book offering a rich analysis of Iowa's role in presidential nomination. The book is centered on the idea that rules matter, with a focus on the rules providing that (1) Iowa's elections mechanism is a caucus, rather than a primary, and (2) that Iowa is the first state to vote in the sequential nomination of presidential candidates.

The book is divided into three parts. The first part offers a thorough account of how the Iowa caucuses work and who participates in them and describes the nature of the 2008 Iowa campaigns. The second, and most innovative, part examines how candidate performance in the early contests interacts with media expectations to influence the outcomes of subsequent contests. In the third part, the authors consider options for reforming the presidential nomination process. Throughout the book, the authors rely on impressive new survey data to help develop their arguments.

Chapter 3 describes the rules governing participation in the Iowa Caucus. Almost by historical accident, Iowa finds itself with a nominating caucus and as the first state to act in presidential nominations. The rules of caucus participation differ by party in Iowa. Republicans generally have short meetings with votes cast by paper ballot; Democratic caucuses are large meetings, with public statements of candidate preference and affiliation, all complicated by a proportional allocation of delegates with a minimum threshold requirement.

The authors point to features like same-day registration that make participating in a caucus less costly than participating in a primary, but give relatively little attention to the aspects of caucus participation that are more costly than participating in a primary, where one's preferences are secret, the act of voting is quick, and the polls are open for much of the day.

In Chapter 4, the authors emphasize the role that grassroots campaigning plays in Iowa. They point out that most candidates spend a considerable amount of time in Iowa leading up to the caucus and develop strong local bases of operation. The conventional wisdom is that a strong ground game in Iowa can overcome the hurdle of being less well-known or poorly funded. Using a survey of Iowa voters with information on which candidate contacted voters and what their method of contact was, the authors find that grassroots support is not a substitute for a small campaign war-chest, nor can financial backing overcome the limitations of poorly organized local operations. Rather, the best candidates are those with significant financial resources and a well-established grassroots organization.

In Chapters 5 and 6, the authors evaluate the demographics of Iowa caucus goers. In Chapter 5 they set their sights on the conventional wisdom that only party activists participate in caucuses. Using surveys collected by telephone and in-person interviews of caucus attendees, the authors examine the demographic data in a litany of ways. Most importantly, they find that about 25% of caucus goers consider themselves to be very or extremely active in the party, while the remaining attendees are motivated not by loyalty to a party but by dedication to the candidates or the issues at stake. The authors conclude that while party activists participate at a relatively high rate in the Iowa caucuses, there is little evidence to suggest that they dominate the caucuses.

In Chapter 6, the authors evaluate the demographic characteristics of Iowa caucus attendees relative to other registered voters. They find that caucuses disproportionately represent those who are strong partisans and those who are better educated. In addition, Republican caucus goers were more likely to be Protestants or born-again Christians. Yet on most other dimensions—including income—caucus attendees tend to be roughly similar to other Iowa registered voters.

In the second part of the book, the authors consider Iowa's place in the national primary season, focusing on the sequential nature of the primaries. In Chapter 7, they demonstrate that success in Iowa and New Hampshire is dependent on an interaction of vote share and media expectations. They make the interesting point that there is no threshold for a candidate to be “successful” in Iowa. A 25% vote share can either be a “comfortable second” or an “overwhelming defeat” depending on expectations (p. 144). Candidates that are able to outperform their incoming expectations are those that do well in the subsequent contests.

In Chapter 8, the authors find that early primaries influence voter perceptions of a candidate's viability in the primary and electability in the general election and, as a consequence, alter voter decisions in later races. The results from a pre/post Super Tuesday survey show that a voter's assessment of a candidate's long term success were influenced by the candidate's success in Iowa and New Hampshire.

In Chapter 9, the authors use a variety of pre-election polls to determine how Iowans' campaign participation and political interest relates to a national sample. They find that Iowans participate in the nominating process at a higher rate than citizens in other states, attributing this to the highly salient and intensely competitive nature of the Iowa caucuses.

The last section of the book considers public support for reforms to the nominating process. In Chapter 10, the authors consider either (1) rotating which states vote first while maintaining sequential contests, or (2) holding a national primary akin to the presidential elections. In a national survey, they find that there is little objection to the status quo: only one in three respondents say that Iowa and New Hampshire have too much influence in the primary (p. 223). Nonetheless, when provided with alternatives, respondents favored either a national primary or rotating the order of the states. On the whole, the authors make the interesting finding that self-interest looms large: those in big states prefer a national primary, those in smaller states prefer rotating the order of the states, and Iowa voters oppose any reform (p. 239).

The final chapter does a nice job of pulling together the various themes of the book, while also offering some suggestions for modest reforms to the role Iowa plays in the nominating process. They note that major reform is unlikely, but do recommend that the parties, particularly the Democrats, release more information on how candidate support is distributed among caucus attendees, thus improving information about candidate viability.

There are, however, areas for improvement. I wish the authors pushed further in Chapter 4 to determine the independent effects of campaign spending and grassroots organization on caucus support. I also wish they would have compared their measure of party activism in Chapter 5 with other more common measures to make sure that their results were not driven by the method of measurement. But these are minor quibbles and the fact that the book generates new questions is a testament to its importance. Why Iowa? is an important, well-written, and accessible book that breaks new ground in understanding presidential nominations and electoral institutions and deepens our knowledge of political participation.