The study develops a simple model where workers can obtain a job through either their strong or weak ties. It shows that increasing the time spent with weak ties raises the employment rate of workers. It also shows that when the job-destruction rate or the job-information rate increases, workers choose to rely more on their weak ties to find a job. The model is extended so unemployed workers can also learn of a vacancy directly from an employer. Results show that equilibrium employment and time spent with weak ties are sometimes, but not in all cases, positively related.

We develop a simple multilayer network model in which agents allocate effort across layers with heterogeneous structures, subject to an aggregate effort constraint. Incentives are shaped by agents’ network positions within each layer, and equilibrium behavior reflects both within- and cross-layer interactions. We analyze how shocks propagate through the network and characterize optimal targeting interventions. Our results show that effective policy design must account for effort allocation across layers. We also demonstrate that predictions from monolayer models can diverge sharply from those of multilayer models, underscoring the importance of accounting for network complexity in both empirical and policy analyses.

We study imperfect competition in the labor market when both workers and firms are heterogeneous. When firms cannot observe workers' skill, firms pay workers equal wages, but workers absorb training costs. When firms can identify worker types, firms pay different net wages to different workers. Voters select the level of general education that is financed by a lump‐sum tax. Workers are on average better off when firms can observe workers' skill for a given level of general human capital, but the median voter prefers a higher level of general human capital when firms cannot observe worker types.

The aim of this article is to analyze the effects of housing discrimination on the wages and unemployment rates of black workers. The unemployment effect is first analyzed using a simple minimum‐wage model. An efficiency‐wage model is then adopted in order to endogenize both unemployment and wages. Under both models, suburban housing discrimination leads to a higher unemployment rate for blacks in the central city than in the suburbs. Under the efficiency‐wage model, black wages are also lower in the center. The analysis thus generates a link between unemployment and a seemingly unrelated phenomenon: racial discrimination in the housing market.

We develop a model that shows that, at the Nash equilibrium, the outcome of each individual embedded in a network is proportional to his/her Katz-Bonacich centrality measure. This measure takes into account both direct and indirect friends of each individual, but puts less weight to his/her distant friends. We then bring the model to the data using a very detailed dataset of adolescent friendship networks. We show that, after controlling for observable individual characteristics and unobservable network specific factors, a standard deviation increase in the Katz-Bonacich centrality increases the pupil school performance by more than 7% of one standard deviation.

We survey the literature on the economic consequences of the structure of social networks. We develop a taxonomy of “macro” and “micro” characteristics of social-interaction networks and discuss both the theoretical and empirical findings concerning the role of those characteristics in determining learning, diffusion, decisions, and resulting behaviors. We also discuss the challenges of accounting for the endogeneity of networks in assessing the relationship between the patterns of interactions and behaviors.

Finite population noncooperative games with linear-quadratic utilities, where each player decides how much action she exerts, can be interpreted as a network game with local payoff complementarities, together with a globally uniform payoff substitutability component and an own-concavity effect. For these games, the Nash equilibrium action of each player is proportional to her Bonacich centrality in the network of local complementarities, thus establishing a bridge with the sociology literature on social networks. This Bonacich–Nash linkage implies that aggregate equilibrium increases with network size and density. We then analyze a policy that consists of targeting the key player, that is, the player who, once removed, leads to the optimal change in aggregate activity. We provide a geometric characterization of the key player identified with an intercentrality measure, which takes into account both a player's centrality and her contribution to the centrality of the others.

We study opinion dynamics in a social network consisting of two groups. Agents update their opinions by conforming to members of their own group while rejecting the views of the opposing group (affective polarization), and by listening to a media outlet that may provide biased information. We characterize the long-run opinions and identify when affective polarization and media bias lead to ideological polarization, persistent disagreement, or failures of learning. We also derive when information interventions or censorship improve the accuracy of average opinions and reduce disagreement, and when they backfire: better information helps only under specific media bias configurations and when directed to the agents we identify as most effective at propagating it through the network.

This article investigates whether virtual contact, initiated through a documentary film, can promote interethnic harmony. We carried out a cluster-randomized field experiment involving over 3,300 households across 121 multiethnic villages in Bangladesh. We find that a documentary film, designed to humanize the ethnic-minority Santals and evoke empathy among the ethnic majority Bengalis, increased the ethnic majority’s prosociality toward minorities, though the strength of the evidence varies by treatment arm and outcome. Using emotion-detecting software to analyze facial expressions during the film viewing suggests that the documentary elicited emotional responses consistent with empathy. We do not find evidence that the intervention reduced the prevalence of negative stereotypes and discriminatory opinions toward minorities. In villages assigned to target network-central people, we find positive behavioral effects on untreated individuals, including Santals, and village-level administrative data suggest a reduction in police complaints in those villages. About five months after the intervention, we conducted a casual-work field experiment involving 720 participants from the main intervention. In this task, pairs of ethnic-majority and minority participants jointly produced paper bags for a local supplier under a piece-rate compensation scheme. We find positive treatment effects on productivity for both ethnic groups, with effects concentrated in villages where network-central people were treated. For the ethnic majority, increased prosociality, and for the ethnic minority, reciprocity or peer pressure may have contributed to increased productivity. Overall, our findings suggest that virtual contact and social networks may help promote harmony in multiethnic communities.

We study a coordination game among agents in a network. The agents choose whether to take action (e.g. adopting a new technology) in an uncertain environment that yields increasing value in the actions of neighbours. We develop an algorithm that fully partitions the network into communities (coordination sets) within which agents have the same propensity to adopt. Our main finding is that a novel measure of network connectedness, which we term “social connectedness,” determines the propensity to adopt for each agent. Social connectedness captures both the number of links each agent has within her community (interconnectedness) as well as the number of links she has with members of other communities who have a higher propensity to adopt (embeddedness). There is a single coordination set if and only if the network is balanced—that is, the average degree of each subnetwork is no larger than the average degree of the network. Finally, we demonstrate that contagion is localized within coordination sets, such that a shock to an agent uniformly affects this agent and all members of her coordination set but has no impact on the other agents in the network.