This book elaborates an aspirations-capabilities framework to advance our understanding of human mobility as an intrinsic part of broader processes of social change. In order to achieve a more meaningful understanding of agency and structure in migration processes, this framework conceptualizes migration as a function of aspirations and capacities to migrate within given sets of perceived geographic opportunity structures. It distinguishes between instrumental (means to an end) and intrinsic (directly affecting well-being) dimensions of human mobility. This produces a view in which moving and staying are seen as complementary manifestations of migratory agency and in which human mobility is defined as the ability of people to choose where to live, including the option to stay, rather than as the act of moving or migrating itself. Drawing on the concepts of positive and negative freedom (as manifestations of the widely varying structural conditions under which migration occurs), the book conceptualizes how macro-structural change shapes people's migratory aspirations and capacities.