The central goal of the book is to demonstrate that new party formation is fundamentally a strategic interaction between “potential” new parties and existing parties. Both the introduction and the first historical or descriptive chapter are engaged in demonstrating the nature of this strategic interaction, which is the same regardless of the class of new party (environmental or nationalist), the institutional constraints, and historical period. In Chapter 2, Hug takes us through the formation of three new parties (the Greens in the Netherlands in the 1980s, the National Socialist German Workers Party [NSDAP] in Weimar Germany, and the British Social Democratic Party in 1981) by describing the political and institutional environment in which each new party was initially created. The selection of these very different parties is used to demonstrate that in each case, despite the historical and institutional variations, the underlying strategic interactions are the same and should therefore be incorporated in a generalized theory of new party formation.

In Chapter 3, Hug develops this interaction more formally into a simplified “game” between two actors: the potential new party and a single established party. In this game, the potential new party makes demands and the existing party must decide how to respond to them. Essential in Hug's approach is the emphasis on the behavior of the existing party, which must decide whether or not to incorporate the demands of the potential party into its policy agenda. Essentially, the established party must make a cost–benefit analysis based on its beliefs about the strength of the potential party and the costs of fulfilling its demands. Demands can be high or low, and potential parties may be strong or weak. While the established party is assumed to have perfect information about the costs of the demands, it has only incomplete information about the strength of the potential party, which, on the other hand, is assumed to know both its own strength and the cost of its demands. It must decide whether to make highcost or low-cost demands on the basis of what it thinks are the chances that those demands will be met by the established party.

The model necessarily simplifies the true situation as all first-stage models must, but these simplifications deserve more attention than is given to them in the text. In particular, Hug implicitly makes the assumption that the potential parties are interested in specific policy outcomes alone and that these are outcomes that can be achieved by the established parties through the normal policy process. This ignores the existence of antisystem parties that do not want simple policy changes but changes in the system as a whole (an aspect of the German NSDAP that is largely ignored in Chapter 2). While it is certainly possible to constrain the theory to only those potential parties wishing to work within the existing political system or making politically acceptable demands, this should be done explicitly.

Hug also asserts that potential parties would always prefer simply to have their demands met without forming a party (see, in particular, Figure 3.2 and Assumption 1, p. 47). This assumes that policy demands are always more important than participation in the governing process. He states that “if the established party accepts the demand the game ends and no new party appears on the electoral scene” (p. 45), an assumption that merits some discussion, even in a simplified game.

An additional aspect of the game that causes some confusion is the inclusion of an additional dimension to the cost–benefit calculus of the established party. Weak potential parties are divided into two distinct categories, credible versus noncredible, largely on the basis of the institutional costs of party formation and the expected benefits to the potential party in terms of electoral success (despite its being weak). The problem with this addition is that it tends to lead Hug into contradictions and, in some cases, tautological reasoning. The assumption has already been made that the established parties do not know if they are dealing with a strong or weak party, and yet Hug claims (p. 55) that the established party “knows whether a weak new party is credible” and that “the established party can condition its decisions on the credibility of the weak new parties.” But this assumes that the established party knows it is dealing with a weak party to begin with.

When discussing the implication of formation (institutional) costs, Hugs states in Implication 2 (p. 57) that “if the weak potential new party is a credible challenger, higher costs of forming a party decrease the likelihood of new parties emerging. If the weak type is not a credible challenger, changes in the costs of forming a new party do not alter the likelihood of new parties emerging.” But remember that the “cost” of new party formation is what makes a weak party credible or not credible to begin with, and so the implication is, in effect, tautological. The significance of this dilemma is increased because it is carried through the empirical analysis in Chapter 5, in particular, on pages 99 to 104 and 113 to 115.

The empirical work of the book is found in Chapters 5 and 6. Chapter 5, in essence, tests the predictions of the theoretical model of new party formation, and Chapter 6 makes some tentative forays into predicting the electoral success of the new parties. Once again here the work is essentially sound and quite informative, but there are some assumptions and choices that reduce the strength of the findings. One is the decision to rely primarily on secondary sources for all of the data collected. In some cases, this is understandable because of the difficulty of the data collection involved or the immutability of the information (national laws on the number of signatures required to gain access to electoral ballot). In other cases (economic indicators), the reliance on the data of others is less understandable as this often leads to the use of older data or data that is not well matched with the electoral cycle being analyzed.

The data analysis itself is quite thorough and does lend significant (albeit at times mixed) support for the underlying thesis of the book. This is important because despite some weaknesses, Hug does achieve his primary goal of demonstrating that the emergence of new parties in Western democracies can be understood from a game theoretical perspective and that this approach supports the development of generalizable theories about the process as a whole. By promoting a theoretical, as opposed to descriptive, approach to analyzing new party formation, the book makes a substantial contribution to the new parties literature and points the way forward for future scholars.