A large and growing literature links high levels of ethnic diversity to low levels of public goods provision. Yet although the empirical connection between ethnic heterogeneity and the underprovision of public goods is widely accepted, there is little consensus on the specific mechanisms through which this relationship operates. We identify three families of mechanisms that link diversity to public goods provision—what we term “preferences,” “technology,” and “strategy selection” mechanisms—and run a series of experimental games that permit us to compare the explanatory power of distinct mechanisms within each of these three families. Results from games conducted with a random sample of 300 subjects from a slum neighborhood of Kampala, Uganda, suggest that successful public goods provision in homogenous ethnic communities can be attributed to a strategy selection mechanism: in similar settings, co-ethnics play cooperative equilibria, whereas non-co-ethnics do not. In addition, we find evidence for a technology mechanism: co-ethnics are more closely linked on social networks and thus plausibly better able to support cooperation through the threat of social sanction. We find no evidence for prominent preference mechanisms that emphasize the commonality of tastes within ethnic groups or a greater degree of altruism toward co-ethnics, and only weak evidence for technology mechanisms that focus on the impact of shared ethnicity on the productivity of teams.

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T he toll of civil conflict is largely borne by civilian populations, as warring factions target noncombatants through campaigns of violence. But significant variation exists in the extent to which warring groups abuse the civilian population: across conflicts, across groups, and within countries geographically and over time. Using a new dataset on fighting groups in Sierra Leone, this article analyzes the determinants of the tactics, strategies, and behaviors that warring factions employ in their relationships with noncombatants. We first describe a simple logic of extraction which we use to generate hypotheses about variation in levels of abuse across fighting units. We then show that the most important determinants of civilian abuse are internal to the structure of the faction. High levels of abuse are exhibited by warring factions that are unable to police the behavior of their members because they are more ethnically fragmented, rely on material incentives to recruit participants, and lack mechanisms for punishing indiscipline. Explanations that emphasize the importance of local community ties and contestation do not find strong support in the data.

How does the resource base of a rebel group impact its membership, structure, and behavior? While scholars, analysts, and policy makers increasingly link natural resources to the onset and duration of civil war, this article explores how resource endowments shape the character and conduct of rebel groups. This article identifies a rebel “resource curse” much like the one that undermines state institutions in resource-rich environments. While the presence of economic endowments makes it possible for leaders to recruit on the basis of short-term rewards, these groups are flooded with opportunistic joiners who exhibit little commitment to the long-term goals of the organization. In resource-poor environments, leaders attract new recruits by drawing on social ties to make credible promises about the private rewards that will come with victory. Opportunistic joiners stay away from these movements, leaving a pool of activist recruits willing to invest their time and energy in the hope of reaping large gains in the future.

Since 1989, international efforts to end protracted conflicts have included sustained investments in the disarmament, demobilization, and reintegration (DDR) of combatants. Yet while policy analysts have debated the factors that contribute to successful DDR programs and scholars have reasoned about the macro conditions that facilitate successful peace building, little is known about the factors that account for successful reintegration at the micro level. Using a new dataset of ex-combatants in Sierra Leone, this article analyzes the individual-level determinants of demobilization and reintegration. Past participation in an abusive military faction is the strongest predictor of difficulty in achieving social reintegration. On economic and political reintegration, we find that wealthier and more educated combatants face greater difficulties. Ideologues, men, and younger fighters are the most likely to retain strong ties to their factions. Most important, we find little evidence at the micro level that internationally funded programs facilitate demobilization and reintegration.

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Developed democracies are settling an increased number of refugees, many of whom face challenges integrating into host societies. We developed a flexible data-driven algorithm that assigns refugees across resettlement locations to improve integration outcomes. The algorithm uses a combination of supervised machine learning and optimal matching to discover and leverage synergies between refugee characteristics and resettlement sites. The algorithm was tested on historical registry data from two countries with different assignment regimes and refugee populations, the United States and Switzerland. Our approach led to gains of roughly 40 to 70%, on average, in refugees' employment outcomes relative to current assignment practices. This approach can provide governments with a practical and cost-efficient policy tool that can be immediately implemented within existing institutional structures.

Recent assaults on foreign-funded civil society groups in Egypt and Russia reflect a worrisome trend: Since 2002, twenty countries have updated their laws to restrict foreign funding to NGOs. Under what conditions do governments set these restrictions in place? Using original data from nearly 100 countries and case studies of regime behavior in East Africa and the former Soviet Union, we find that vulnerable governments restrict foreign support to civil society when they feel vulnerable to domestic challenges. Yet, worries about international retaliation can restrain such behavior if governments believe that clamping down will cost them more than it is worth.