Karla Hoff is a lead economist in the World Bank's Development Research Group and a visiting professor at Columbia University. She was co-director of the World Development Report 2015, Mind, Society, and Behavior. She has used applied theory, analysis of observational data, and lab-in-the-field experiments to study social interactions that impede economic development: learning spillovers, enforcement costs, corruption, low homeownership rates that undermine investment in neighborhoods, and stereotype threat. In behavioral economics, her work highlights the role of social constructions, such as caste, in changing how people see themselves and see others. Social constructions can sustain “equilibrium fictions”—differences between groups that are inherently the same. She co-edited two books—The Economics of Rural Organization and Poverty Traps.