Research on migration and development has recently changed, in two ways. First, it has grown sharply in volume, emerging as a proper subfield. Second, while it once embraced principally rural-urban migration and international remittances, migration and development research has broadened to consider a range of international development processes. These include human capital investment, global diaspora networks, circular or temporary migration, and the transfer of technology and cultural norms. For this special issue, we present a selection of frontier migration-and-development research that instantiates these trends.