International institutions play a central role in world politics. Over the past two decades, the theory of international institutions has been one of the most vibrant areas of research in international relations. Curiously, however, regional institutions—except for European institutions—occupy an insignificant place in institutional theories. Focusing on regional international institutions, this volume, edited by two distinguished international relations scholars, addresses two puzzles that are central to theories of international institutions. The first puzzle deals with the source of institutional design. Specially, how do regional institutions vary in design and what explains their varying designs? The second puzzle deals with the effects of institutional design. Specifically, does the varying designs of regional institutions account for their varying efficacy?

This volume builds on the rational design of international institutions project in international relations scholarship, and yet seeks to go beyond it in three ways. First, it investigates not only what explains the design of regional institutions but also how such designs matter. Second, it examines actors' concerns with utility and efficacy, but also with moral considerations. Third, it seeks to correct what the editors believe is a Eurocentrism that has characterized the study of institutional design.

Relaxing earlier definitions of institutional design, the editors of this volume define institutional design so as to include both formal and informal rules and organizational features. The volume examines five key elements of institutional design: membership, scope, formal rules, norms, and mandate. By covering such a wide range of design features, the volume seeks to enable “a more complete test of a fuller range of plausible hypotheses”—not just the rationalist but also the constructivist—at the cost of “conceptual tractability” (p. 22). One could argue, however, that while the empirical chapters give us a rich sense of how certain factors are relevant, they do not deliver real “tests.” As such, one can continue to wonder whether, then, the cost of conceptual tractability is adequately justified, particularly if a clear conceptual framework is what is needed in the first place to guide empirical tests.

To understand why regional institutions take the forms they do, the volume examines a wide range of independent variables that includes types of cooperation problems, the number of actors, the ideologies and identities of the actors, systemic and subsystemic power distributions, domestic politics, extra-regional institutions and non-state actors, as well as history.

While each empirical chapter devotes its first half to a study of how these independent variables affect any or all design features, each devotes its second half to examining how the resulting design features influence the efficacy of each regional institution. To examine the efficacy of regional institutions, the volume takes up cooperation as a dependent variable. But it disaggregates cooperation into six specific elements: the degree of normative and preference change, the degree of policy convergence across actors, the degree of institutionalization and legalization, the different routes to the above changes, the degree of adjustment of prior policies, and finally, the degree to which the institution has achieved its set goals.

The volume recognizes the daunting difficulty in establishing a causal relationship between design and efficacy. That is the problem of endogeniety. Not only may states choose to support the type of design that produces their preferred outcomes, but also, design and efficacy influence one another over time. Despite these difficulties that might limit the generalizability of the volume's findings, the empirical chapters covering major regional institutions generate some very interesting insights.

Concerning the effects of institutional design, the volume finds that institutional design features matter in how subsequent cooperation unfolds. For instance, the volume suggests that the initial or original design features of institutions “set limits to change induced by functional imperatives or new normative goals adopted by regional institutions” (p. 264). These findings contribute to our understanding of how institutions develop and evolve. Beyond this, however, we may also like to know how each element of institutional design contributes in which way to which aspect of efficacy, and how these diverse casual channels interact with each other. Finally, if we think of design features as elements of the structure in which agents interact with one another, then the importance of these environmental variables should perhaps vary with agents' choices and actions. While it is not difficult to accept that design elements matter, we may next want to know how and how much they matter, for instance, as compared to agent actions.

The most interesting findings from this volume concern the sources of institutional design. These findings speak not only to the rational design of international institutions project that this volume builds on, but also to the latest development in theories of international institutions. While most of the independent variables seem to have influenced institutional design in some cases but not others, one factor has shaped institutional design in all regional institutions covered in this volume. That factor is domestic politics. In particular, concern with domestic regime survival seems an overriding factor in the design of regional institutions. The emphasis on sovereignty and noninterference, shared in the developing world, is not entirely absent in the most institutionalized world of the EU, either. Such important commonalities across regional institutions keep in perspective the differences that do exist among them.

This and other interesting findings further suggest many important questions for future research. If political leaders are similarly concerned with regime survival in designing regional institutions, why do regional institutions nevertheless look different? In other words, why do different features of institutions satisfy leaders with the same concerns with domestic politics? Furthermore, why do countries with different domestic political environments want the same features of regional institutions? Complicated further by the unresolved endogeniety issue, do regional institutions that are designed with the concern of noninterference in mind nevertheless have powerful effects on national policies? If so, how? By opening up such an important research agenda, this volume represents a major contribution to theories of international institutions.