A new introduction to a timeless dynamic: how the movement of humans affects health everywhere.International migrants compose more than three percent of the world s population, and internal migrants those migrating within countries are more than triple that number. Population migration has long been, and remains today, one of the central demographic shifts shaping the world around us. The world s history and its health is shaped and colored by stories of migration patterns, the policies and political events that drive these movements, and narratives of individual migrants. Migration and Health offers the most expansive framework to date for understanding and reckoning with human migration s implications for public health and its determinants. It interrogates this complex relationship by considering not only the welfare of migrants, but also that of the source, destination, and ensuing-generation populations. The result is an elevated, interdisciplinary resource for understanding what is known and the considerable territory of what is not known at an intersection that promises to grow in importance and influence as the century unfolds.