There are an estimated 750 million internal migrants in the world, yet the effects of access to internal migration for rural households are not well understood. Internal migrants may provide wealth transfers, insurance or credit to households remaining in rural areas. This paper exploits two unique features of China's history to study the impact of relaxing migration constraints on the outcomes and choices of agricultural households: reforms to the household registration (hukou) system that relaxed restrictions on migration, and historical, centrally-planned migration flows. We show that historical flows of temporary migration due to a government policy called the "sent-down youth" (SDY) program created lasting inter-province links, so that decades later, reforms to the hukou system in cities which sent SDY increased migration in provinces where those SDY were sent. Using this variation, we find that improved access to migration leads to higher levels of consumption and lower consumption volatility for rural households. Furthermore, household production decisions change, with a shift into high-risk, high-return activities including animal husbandry and fruit farming.

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. Links between households that were unlikely to ever borrow from microfinance are at least as likely to disappear as links involving likely borrowers. We replicate these surprising findings in the context of a randomized controlled trial in Hyderabad, where a microfinance institution randomly selected neighborhoods to enter first. Four years after all neighborhoods were treated, households in early-entry neighborhoods had credit access longer and had larger loans. We again find fewer social relationships between households in early-entry neighborhoods, even among those ex-ante unlikely to borrow. Because the results suggest global spillovers, which are inconsistent with standard models of network formation, we develop a new dynamic model of network formation that emphasizes chance meetings, where efforts to socialize generate a global network-level externality. Finally, we analyze informal borrowing and the sensitivity of consumption to income fluctuations. Households unlikely to take up microcredit suffer the greatest loss of informal borrowing and risk sharing, underscoring the global nature of the externality.

In village economies, insurance networks are key to smoothing shocks, while production networks can propagate them. The interplay of these networks is crucial. We show that a significant health expenditure shock to one household propagates to other linked households via supply-chain and labor networks. Imperfectly insured households adjust production decisions--cutting input spending and reducing labor hiring--affecting households with whom they trade inputs and labor. Household businesses proximate to shocked households in the supply chain network experience reduced local sales, and those proximate in the labor network experience a lower probability of working locally. As a result, indirectly shocked households' earnings and consumption fall. These declines persist over several years because networks are rigid: households appear unable to form new linkages when existing links experience negative shocks. Propagation is a function of access to insurance networks: well-insured households do not cut spending when hit by shocks, leading to minimal propagation. A simple back-of-the-envelope exercise suggests that the total magnitude of indirect effects may be larger than the direct effects and that social (village-level) gains from expanding safety nets such as health insurance may be substantially higher than private (household-level) gains.

Can microcredit help unlock a poverty trap for some people by putting their businesses on a different trajectory? Could the small microcredit treatment effects often found for the average household mask important heterogeneity? In Hyderabad, India, we find that "gung ho entrepreneurs" (GEs), households who were already running a business before microfinance entered, show persistent benefits that increase over time. Six years later, the treated GEs own businesses that have 35% more assets and generate double the revenues as those in control neighborhoods. We find almost no effects on non-GE households. A model of technology choice in which talented entrepreneurs can access either a diminishing-returns technology, or a more productive technology with a fixed cost, generates dynamics matching the data. These results show that heterogeneity in entrepreneurial ability is important and persistent. For talented but low-wealth entrepreneurs, short-term access to credit can indeed facilitate escape from a poverty trap.

We report on a large randomized controlled trial of hospital insurance for above-poverty-line Indian households. Households were assigned to free insurance, sale of insurance, sale plus cash transfer, or control. To estimate spillovers, the fraction of households offered insurance varied across villages. The opportunity to purchase insurance led to 59.91% uptake and access to free insurance to 78.71% uptake. Access increased insurance utilization. Positive spillover effects on utilization suggest learning from peers. Many beneficiaries were unable to use insurance, demonstrating hurdles to expanding access via insurance. Across a range of health measures, we estimate no significant impacts on health.

We report on a large randomized controlled trial of hospital insurance for above-poverty-line Indian households. Households were assigned to free insurance, sale of insurance, sale plus cash transfer, or control. To estimate spillovers, the fraction of households offered insurance varied across villages. The opportunity to purchase insurance led to 59.91% uptake and access to free insurance to 78.71% uptake. Access increased insurance utilization. Positive spillover effects on utilization suggest learning from peers. Many beneficiaries were unable to use insurance, demonstrating hurdles to expanding access via insurance. Across a range of health measures, we estimate no significant impacts on health.

Can microcredit help unlock a poverty trap for some people by putting their businesses on a different trajectory? Could the small microcredit treatment effects often found for the average household mask important heterogeneity? In Hyderabad, India, we find that "gung ho entrepreneurs" (GEs), households who were already running a business before microfinance entered, show persistent benefits that increase over time. Six years later, the treated GEs own businesses that have 35% more assets and generate double the revenues as those in control neighborhoods. We find almost no effects on non-GE households. A model of technology choice in which talented entrepreneurs can access either a diminishing-returns technology, or a more productive technology with a fixed cost, generates dynamics matching the data. These results show that heterogeneity in entrepreneurial ability is important and persistent. For talented but low-wealth entrepreneurs, short-term access to credit can indeed facilitate escape from a poverty trap.

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. Links between households that were unlikely to ever borrow from microfinance are at least as likely to disappear as links involving likely borrowers. We replicate these surprising findings in the context of a randomized controlled trial in Hyderabad, where a microfinance institution randomly selected neighborhoods to enter first. Four years after all neighborhoods were treated, households in early-entry neighborhoods had credit access longer and had larger loans. We again find fewer social relationships between households in early-entry neighborhoods, even among those ex-ante unlikely to borrow. Because the results suggest global spillovers, which are inconsistent with standard models of network formation, we develop a new dynamic model of network formation that emphasizes chance meetings, where efforts to socialize generate a global network-level externality. Finally, we analyze informal borrowing and the sensitivity of consumption to income fluctuations. Households unlikely to take up microcredit suffer the greatest loss of informal borrowing and risk sharing, underscoring the global nature of the externality.