Formal financial institutions can have far-reaching and long-lasting impacts on informal lending and information networks. We first study 75 villages in Karnataka, 43 of which were exposed to microfinance after we first collected detailed network data. Networks shrink more in exposed villages....

During the COVID-19 epidemic, many health professionals started using mass communication on social media to relay critical information and persuade individuals to adopt preventative health behaviors. Our group of clinicians and nurses developed and recorded short video messages to encourage...

We evaluate a large-scale set of interventions to increase demand for immunization in Haryana, India. The policies under consideration include the two most frequently discussed tools--reminders and incentives--as well as an intervention inspired by the networks literature. We cross-randomize...

Agricultural extension programs often train a few farmers and count on diffusion through social networks for the innovation to spread. However, if markets are imperfectly integrated, this may also inflict negative externalities. In a two-step experiment of an agronomy training program among...

Following the widespread adoption of free primary education, African policymakers are now considering making secondary school free, but little is known about the private and social benefits of free secondary education. We exploit randomized assignment to secondary school scholarships among 2,064...

COVID-19 vaccines are widely available in wealthy countries, yet many people remain unvaccinated. Understanding the effectiveness -- or lack thereof -- of popular vaccination campaign strategies is therefore critical. In this paper, we report results from two studies that tested strategies...

An enduring puzzle regarding technology adoption in developing countries is that new technologies often diffuse slowly through the social network. Two of the key predictions of the canonical epidemiological model of technology diffusion are that forums to share information and higher returns to...

The mental health of the elderly in low- and middle-income countries (LMICs) is a largely neglected subject, both by policy and research. We combine data from the health and retirement family of surveys in seven LMICs (plus the US) to document that depressive symptoms among those aged 55 and...