Thesis: This dissertation studies how social interactions have impacts on economic outcomes for marginalized groups in lower- and middle-income countries, and how inequalities in human capital can propagate and be addressed. The first chapter, Silence to Solidarity: Using Group Dynamics to Reduce Anti-Transgender Discrimination in India, studies how discrimination is affected by communication about a marginalized minority. Individual-level discrimination is often attributed to deep-seated prejudice that is difficult to change. But at the societal level, we sometimes observe rapid reductions in discriminatory preferences, suggesting that social interactions and the communication they entail might drive such shifts. I examine whether discrimination can be reduced by two types of communication about a minority: (i) horizontal communication between majority-group members, or (ii) top-down communication from agents of authority (e.g., the legal system). I run a field experiment in urban India (N=3,397) that measures discrimination against a marginalized community of transgender people. Non-transgender participants are highly discriminatory: in a control condition, they sacrifice 1.9x their daily food expenditure to avoid hiring a transgender worker to deliver groceries to their home. But horizontal communication between participants sharply reduces discrimination: participants who were earlier involved in a group discussion with two of their neighbors no longer discriminate on average, even when making private post-discussion choices. This effect is 1.7x larger than the effect of top-down communication that informs participants about the legal rights of transgender people. The discussion’s effects are not driven by virtue signaling or correcting a misperceived norm. Instead, participants appear to persuade each other to be more pro-trans, partly because pro-trans participants are the most vocal in discussions. The second chapter, Menstrual Stigma, Hygiene, and Human Capital: Experimental Evidence from Madagascar, joint with Karen Macours and Julieta Vera Rueda, studies how menstrual stigma can be addressed using positive deviants (those who are willing to speak out against such stigma), and how hygiene-focused programs can generate human capital improvements in low income schools. The chapter presents results from an RCT in 140 schools in Madagascar that targets both hygiene practices and menstrual stigma. First, we show that a bundle of interventions (sanitation infrastructure, menstrual products, and teacher sensitization) leads to substantial (0.15 SD) improvements in learning tests and school marks, without affecting attendance or health. Girls’ heart rate during the endline survey is 0.12 SD lower in treatment schools, suggesting that learning benefits may come from reduced stress and an improved psychosocial environment at school. Second, we evaluate the additional effect of nominating and coaching “young girl leaders” – school girls willing to speak out against menstrual stigma – to spread positive messages about hygiene and menstruation. The combined program generates substantial improvements in hygiene knowledge and behavior (0.32-0.56 SD) and in menstrual stigma (0.5 SD), and the Young Girl Leader component significantly increases the impact on all of these dimensions. The third chapter, Critical Periods in Cognitive and Socioemotional Development: Evidence from Weather Shocks in Indonesia, studies how the timing of shocks in early childhood can have long-lasting consequences on the development of an individual’s human capital. Early life circumstances are important determinants of long-run human capital and wellbeing outcomes. The first 1000 days of life are often cited as a ‘critical period’ for child development, but this notion has rarely been directly tested […]