In this article, the authors bring together research on horizontal inequality, geographic dispersion of ethnic groups and crosscutting cleavages to present a more holistic theory of ethnic structure and civil war onset. The authors argue that rebel leaders are thwarted in their mobilization efforts in highly crosscutting societies due to a lower probability of potential combatants identifying with nationalist goals, decreased ability to exert social control, and diminished in-group communication.Using cross-national data from over 100 countries, the authors provide evidence that civil war onset is an average of nearly twelve times less probable in societies where ethnicity is crosscut by socioeconomic class, geographic region, and religion.

Many studies in economics and political science include the concept of ethnic diversity as a key independent variable in empirical studies. To date, however, only single-dimensional measures of ethnic diversity, such as ethnic fractionalization, have been available. In this paper, I define and measure three multidimensional characteristics of social structure-cross-cuttingness, cross-fractionalization, and subgroup fractionalization-and present a new cross-national data set comprised of indices along combinations of five cleavages: race, language, religion, region, and income. After addressing important definitional and measurement issues, I discuss the data and show how their inclusion in economic growth regressions reopens the theoretical debate regarding the influence of ethnic diversity, indicating the potential for these new indices to shed light on the role of ethnic diversity (and social structure more generally) with regards to a number of phenomena of concern to political scientists.

Many studies in economics and political science include the concept of ethnic diversity as a key independent variable in empirical studies. To date, however, only single-dimensional measures of ethnic diversity, such as ethnic fractionalization, have been available. In this paper, I define and measure three multidimensional characteristics of social structure-cross-cuttingness, cross-fractionalization, and subgroup fractionalization-and present a new cross-national data set comprised of indices along combinations of five cleavages: race, language, religion, region, and income. After addressing important definitional and measurement issues, I discuss the data and show how their inclusion in economic growth regressions reopens the theoretical debate regarding the influence of ethnic diversity, indicating the potential for these new indices to shed light on the role of ethnic diversity (and social structure more generally) with regards to a number of phenomena of concern to political scientists. The data set is publicly available from the Inter-University Consortium for Political and Social Research data archives and the Institute for Quantitative Social Science Dataverse Network.

This article seeks to further our understanding of how social structure affects the onset of civil war. Existing studies to date have been inconclusive, focusing only on single-cleavage characteristics of social structure, such as ethnic or religious fractionalization. This study argues that models that do not take into account the relationship between cleavages (or cleavage structure) are biased and thus reach faulty conclusions. With the focus on the cleavages of ethnicity and religion, the effects of two characteristics of cleavage structure on civil war onset (cross-cuttingness and cross-fragmentation) are defined and tested. A new index of ethno-religious cross-cuttingness (ERC), derived from national public opinion surveys, reveals that ERC is a significant determinant of civil war onset when interacted with ethnic fractionalization.

How do changes in electoral rules affect the nature of public policy outcomes? The current evidence supporting institutional theories that answer this question stems almost entirely from quantitative cross-country studies, the data of which contain very little within-unit variation. Indeed, while there are many country-level accounts of how changes in electoral rules affect such phenomena as the number of parties or voter turnout, there are few studies of how electoral reform affects public policy outcomes. This article contributes to this latter endeavor by providing a detailed analysis of electoral reform and the public policy process in Thailand through an examination of the 1997 electoral reforms. Specifically, the author examines four aspects of policy-making: policy formulation, policy platforms, policy content, and policy outcomes. The article finds that candidates in the pre-1997 era campaigned on broad, generic platforms; parties had no independent means of technical policy expertise; the government targeted health resources to narrow geographic areas; and health was underprovided in Thai society. Conversely, candidates in the post-1997 era relied more on a strong, detailed national health policy; parties created mechanisms to formulate health policy independently; the government allocated health resources broadly to the entire nation through the introduction of a universal health care system, and health outcomes improved. The author attributes these changes in the policy process to the 1997 electoral reform, which increased both constituency breadth (the proportion of the population to which politicians were accountable) and majoritarianism.