This paper seeks to lay out—in a comprehensive yet concise way—how migration comes about. It stops short of prescribing particular policy interventions, but lays the foundation for identifying how migration dynamics and their outcomes may be shaped by government policy. The paper presents a model of migration that draws upon recent developments in migration theory. It is broadly applicable across different categories of migrants, including refugees. The model is built around three steps: (1) The formation of a desire for change. This is driven by people’s current conditions, their perception of prospects for the future, and their life aspirations. The desire for change may be focused on personal security, living conditions, professional development, or other spheres of life. (2) The channelling of a desire for change into migration aspirations. People could respond to a desire for change by seeking a future elsewhere. Alternatively, they could pursue local opportunities—either for changing their personal circumstances or contributing to social change. These responses could be constructive (e.g. pursuing education, entrepreneurship, or political activism) or destructive (e.g. radicalization or violent mobilization). (3) The outcomes of migration aspirations. A wish to migrate could be converted into actual migration, depended on opportunities and resources. But it could also result in an unsuccessful migration attempt in the form of death, being trapped en route, or having to return against one’s will. A third outcome is involuntary immobility—wishing to leave but being unable to do so. This is a largely invisible outcome, but a potentially damaging one for individuals and communities.