International migration policy for lower-income countries is still guided by assumptions from an earlier era—when less-educated labor was abundant, skilled emigration was seen purely as ‘brain drain,’ and development was expected to reduce migration. That world is gone. This paper reviews recent research on migration policy in the 21st century, when demographic decline is making labor scarce globally, skilled emigration can yield net long- term gains for origin countries, and development often increases migration pressures for generations. The literature shows that migration, managed through innovative institutions, can sustain fiscal systems in aging economies, spur human capital investment at origin, and accelerate structural change. Migration is not a substitute for development, but a catalyst and major opportunity. Policy priorities include regional free-movement regimes, new destination-country partnerships, restructured skill-training systems for a mobile world, and integrating migration into aid partnerships. Much more research is needed to understand the impacts of these tools.