Abstract: Ethnic polarization is often linked to underdevelopment and poor governance. What amplifies and what mitigates ethnic tensions amongst individuals in a society? This project aims to understand how subtle and moderate changes in context can impact economic behavior. We use behavioral economics experiments to measure altruism, cooperation, and expected generosity in within-group and across-group interactions. Using “priming” within the lab, we identify if these behavioral outcomes vary with the increased situational salience of ethnic identity, national identity, or political competition. We replicate our design at two time points in Nairobi, Kenya (with the second round being close in time to the 2013 national elections) to examine how election proximity might affect behavior, and in the capital (Dar es Salaam) of neighboring Tanzania to explore how differing political histories can shape current social interactions.