This dissertation examines three different topics on cooperation and social inequality. The three chapters have in common that they all study how social structures shape perceptual responses to inequality and cooperative behavior. But they explore different dimensions of these social structures. The first essay is an experimental study on unequal opportunity and beliefs about inequality. Using a novel experimental design based on a two-person card game, this chapter disentangles the causal effect of unequal opportunity and unequal rewards on how individuals perceive inequality. Results generally show winners are more likely to perceive unequal outcomes as fair, attribute results to their skills, and be happy with their outcome. However, they are also sensitive to playing with advantages and are more likely to perceive results as unfair than winners playing with equal opportunity. The second essay is a study on community norms of cooperation and cooperative behavior with strangers. Using unique data on key organizational actors in the Chinese economy, this chapter explores the link between sanctioning mechanisms enabled by different reciprocity structures and cooperation with unknown others. Results generally show that norms of reciprocity developed in business communities are positively related to cooperation with strangers. When city interactions with reciprocity norms are explored, results show that reciprocity norms are more prevalent in cities with more horizontal views on entrepreneurial activity, less resistance from the state, and a strong local market development. Finally, the third essay studies the effect of status rewards on cooperation in a large online community. This chapter introduces a new theoretical mechanism based on a behavioral bias: the ``rest on your laurels'' hypothesis, according to which cumulative status decreases further contributions to collective goods. I collect data from Stack Overflow, a large online community on programming and computing, and build a panel with complete trajectories of status attainment and individual contributions. Using dynamic panel data models, I find that status does decrease cooperation over time, even after accounting for individual heterogeneity and endogeneity between status and cooperation. Together, these essays make important contributions to the study of social inequality, reciprocity, and cooperation.