A case is made for treating international migration as a global business which has both legitimate and illegitimate sides. The migration business is conceived as a system of institutionalized networks with complex profit and loss accounts, including a set of institutions, agents and individuals each of which stands to make a commercial gain. The article focuses on migrant trafficking, the core of the illegitimate business.Migrant trafficking, a subject of growing political concern, is recognized by migration experts and policy makers to be undermining international collaborative efforts to produce ordered migration flows. Trafficking, widely condemned for its inhuman practices and links to international organized crime, is also believed to be increasing in scale and sophistication.Our model conceives of trafficking as an intermediary part of the global migration business facilitating movement of people between origin and destination countries. The model is divided into three stages: the mobilization and recruitment of migrants; their movement en route; and their insertion and integration into labour markets and host societies of destination countries. At each stage of the model we describe the trafficking business, its systematic organization and its methods of operation: its inputs and outputs; its use of a set of common geographical routes; its methods of smuggling migrants; its systems of planning and information‐gathering; and its division into a set of technical and organizational tasks. This division of roles is seen as critical for trafficking’s survival.The model also suggests how through the existence of common routes and networks of contacts, traffickers increasingly channel migrants, thus determining the geography of movement. We also demonstrate the model with available evidence on trafficking mainly in and across Europe and attempt thereby to show how trafficking operates both theoretically and in practice.Our conceptualization of trafficking as a business has important implications for the study of migration and for policy makers. For the former, trafficking blurs meaningful conceptual distinctions between legal and illegal migration. For the latter, trafficking presents new challenges in the management and control of migration flows across borders. In particular it suggests the need to look at immigration controls in new ways, placing sharper focus on the institutions and vested interests involved rather than on the migrants themselves.