Allen Hicken has written a compelling book that advances the literature on party system formation in new democracies. He asks why some new democracies develop party systems comprised of a small number of nationally oriented parties while others do not. This is an important question. As Hicken notes at the outset, parties are the building blocks of democracy, yet in many developing democracies, even in those that score well on most measures of democratic outcomes, parties are weak and party systems fractious.

Hicken starts with the assumption that a party system comprised of a moderate number of nationally oriented parties is desirable for democratic consolidation and asks under what circumstances such systems come into being. His answer is simple—it depends on the incentives that politicians have for coordinating across electoral districts. The greater these “aggregation incentives,” the more likely it is that politicians will coalesce under a single party organization in order to contest national power. The dependent variable—aggregation—is measured by first taking the difference between the effective number of parties at the national level and the average effective number of parties at the electoral district level, and then calculating this difference as a percentage of the number of effective parties at the national level. This yields a measure of “inflation,” indicating the share of the national party system size that can be attributed to poor aggregation.

This institutional approach is elegant and well crafted, and it builds on a strong tradition of comparative literature that explores the impact of electoral rules and constitutional design on party systems in new democracies. Yet Hicken points out that much of the literature on electoral rules focuses on district-level outcomes, where coordination among political actors is facilitated by more direct contact and more immediate results. Understanding national party system formation requires an accounting of politicians' expectations regarding not only how best to translate district-level results into a national win but also whether doing so both requires and adequately rewards coordination: “Cross-district coordination requires that political elites from many localities cooperate by, for example, forging an electoral alliance (a party) and compromising on a set of policy goals and priorities. It is these cross-district attempts at coordination or aggregation that often fail, particularly in developing democracies” (p. 10).

Just as electoral system design cannot fully explain the shape of the national party system, constitutional design alone falls short in explaining party system outcomes. Hicken builds directly on the work of Pradeep Chhibber and Ken Kollman who also demonstrate that similar constitutional designs can produce very party different systems, and that to explain the character of national party systems one must look beyond the electoral rules that predict district-level behavior. Chhibber and Kollman use a comparative study of four federalist systems (the United States, Canada, the UK, and India) to argue convincingly that the distribution of authority between national and subnational governments is an essential factor in determining the type of party system that emerges (The Formation of National Party Systems:Federalism and Party Competition in Canada, Great Britain, India, and the United States, 2004).

Hicken expands on this insight, finding that it is not only the distribution of power across levels of government (vertical centralization) but also the concentration of power within the national government (horizontal centralization) that defines the incentive structure faced by politicians. Politicians calculate the expected payoff from winning power at the national level by gauging both vertical and horizontal centralization. Factors such as a bicameral legislature and the existence of reserve domains of power at the national level reduce horizontal centralization of power in the national government and diminish the likelihood that the largest legislative party will be able to take control of government. The nature of these “aggregation incentives,” he argues, explains the emergence of small numbers of nationally oriented parties in a broad range of new democracies. He carefully tests his theory in 280 elections in 46 countries, including established as well as developing democracies.

Finally, Hicken argues, the incentives for politicians to engage in coordination across electoral districts depends not only on the size of the potential reward for such coordination but also on the likelihood that they will reap that reward. He defines this as the probability that the largest legislative party will capture executive power and provides a careful discussion of the factors that affect politicians' calculation of this probability in presidential and parliamentary systems. The discussion of presidential systems posits a complex chain of calculations by politicians based on the number of candidates, the presence of an incumbent, and the proximity of presidential and legislative elections that is less than fully convincing for a diverse range of cases. The calculation is far more straightforward in parliamentary systems, where the only question is whether or not the largest legislative party normally selects the executive.

The quantitative results, meticulously presented in a single chapter, provide convincing evidence that aggregation “is the product of two factors: (a) the size of the aggregation payoff and (b) the probability that the largest legislative party will capture that payoff” (p. 84). This is true, the author finds, even with high levels of ethnic fractionalization and even where the difficulty of the coordination task is considerable. The results lend support to the idea that democracy can indeed be deliberately constructed across a range of social and cultural contexts and justifies the author's assertion that social cleavages are at best a small part of the explanation for party system formation.

Hicken includes three exhaustively researched chapters that apply the argument in Thailand and the Philippines. These two cases provide a fascinating sustained comparison that spans several decades of social and institutional change in each case, allowing the author to explore and dispatch a number of important rival explanations for the outcomes he observes. Hicken's careful comparison of these two cases, building as it does on his mastery of the intricacies of party politics in Thailand and the Philippines, puts the necessary flesh on the bones of his carefully constructed theoretical model and significantly strengthens the book.

Despite the strengths of the case studies, the focus there as in the rest of the book is on the outcomes of institutional change, rather than on the process through which actors respond to change in order to bring about these outcomes. But what are the mechanics of cross-district coordination and the role of voters and party organization in shaping politicians' cooperative behavior? How does voter behavior affect politicians' responses to institutional change, and with what kind of lag time? Hicken acknowledges that “societal cleavages interact with other (largely institutional) variables to shape the incentives and ability of candidates to coordinate,” but leaves unexamined the question of how they interact (p. 33). Are politicians' responses to institutional change tempered by their knowledge of existing social cleavages? Similarly, politicians are treated as largely unconstrained by their parties. The cases do provide discussions of legislators' behavior, but what is the role of party organizations in electoral districts, or at other levels, in shaping this behavior?

With regard to both the analysis he provides and the questions he leaves as yet unanswered, Hicken has made an important contribution to the comparative study of party formation in developing democracies.