The fast and often chaotic urbanization of the developing world generates both economic opportunity and challenges, like contagious disease and congestion, because proximity increases both positive and negative externalities. In this article, we review the expanding body of economic research on...

We experimentally study the impact of substantially larger enterprise loans, in collaboration with an Egyptian lender. Larger loans generate small average impacts, but machine learning using psychometric data reveals dramatic heterogeneity. Top-performers (i.e., those with the highest predicted...

We study the impact of cognitive behavioral therapy (CBT) for individuals se- lected from the general population of poor households in rural Ghana. Results from 2-3 months after a randomized intervention show strong impacts on mental and physical health, cognitive and socioemotional skills, and...

We study the impact of cognitive behavioral therapy (CBT) for individuals selected from the general population of poor households in rural Ghana. Results from 2-3 months after a randomized intervention show strong impacts on mental and physical health, cognitive and socioemotional skills, and...

The rural northwestern districts of Bangladesh, home to 10 million people, experience a preharvest seasonal famine, locally known as Monga, with disturbing regularity. Surprisingly, outmigration from the Monga-prone districts is not all that common. This research tests whether migration could...

We review the theoretical and empirical literature on commitment devices.A commitment device is any arrangement, entered into by an individual, with the aim of making it easier to fulfill his or her own future plans. We argue that there is growing empirical evidence supporting the proposition...

The rural northwestern districts of Bangladesh, home to 10 million people, experience a preharvest seasonal famine, locally known as Monga, with disturbing regularity. Surprisingly, outmigration from the Monga-prone districts is not all that common. This research tests whether migration could...

We review the theoretical and empirical literature on commitment devices. A commitment device is any arrangement, entered into by an individual, with the aim of making it easier to fulfill his or her own future plans. We argue that there is growing empirical evidence supporting the proposition...

We examine a randomized trial that allows separate identification of peer screening and enforcement of credit contracts. A South African microlender offered half its clients a bonus for referring a friend who repaid a loan. For the remaining clients, the bonus was conditional on loan approval....