The central idea in social economics is that an individual's actions are influenced by the choices and characteristics of peers. This occurs because group (network) membership provides information and shapes beliefs (norms). For both researchers and policymakers, the interest in social economics stems from its ability to explain a range of phenomena including the persistence of urban poverty and the spatial distribution of crime. This dissertation contributes to the literature by providing new empirical evidence on the effects of social interactions. Specifically, the first two chapters examine the impact of neighborhood peers on children by studying housing policy reforms in Chicago using novel administrative data. The third chapter (joint with Lasse Brune and Jason Kerwin) studies how coworkers affect workplace productivity using data from a field experiment.PhDEconomicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/133263/1/ericchyn_1.pd