This thesis makes a contribution to three areas of sociological thought. First, it is concerned with the elaboration and extension of the political economy approach to migration as it is represented in the work of Stephen Castles and his various co-authors. It suggests that the work of Castles, et al., is relatively silent on the role of the state, and ideological relations in the structuration of migration. In seeking to further refine the political economy framework as it is applied to migration, this thesis draws upon two other sets of literature which, in part, have emerged as counters to some of the more economistic of their formulations. In this light, the second area of sociological literature I draw upon is the recent work on the concepts of free and unfree labour. Finally, this thesis is informed by an analysis of recent debates on the concept of racialization. In synthesizing these three strands of sociology, this thesis advances the theoretical claim that political economy oriented theorists should focus on modes of incorporation, or the manner in which foreign-born labour articulates with capital and the state. Within this context, four distinct modes of incorporation under capitalism are identified. These modes of incorporation are designated as: free immigrant labour, unfree immigrant labour, free migrant labour and unfree migrant labour. This thesis suggests that agents are subject to particular modes of incorporation, in part, on the basis on the process of racialization. This thesis uses the cases of late nineteenth and early twentieth century Chinese migration to Canada, and the post-1945 migration of farm labourers, from a number of source countries, including, specifically, the Netherlands, Poland, Germany, and the Caribbean, to the south western Ontario fruit and vegetable industry to highlight the centrality of the state in the process of migration, and the differential modes of incorporation of foreign-born persons into sites in production relations. Furthermore, the process of racialization is seen to have an impact on whether particular groups are allowed entry to a social formation, and upon how they are incorporated into sites in production relations.