The present article has two goals. First, it aims to evaluate if and to what degree social networks understood in terms of social capital are responsible for the process of initiation and perpetuation of undocumented migration, more especially in the case of the migration of undocumented Polish and Bulgarian migrants to Brussels. Secondly, it addresses the assumptions of the social capital theory developed precisely to explain the persistence of undocumented migratory and to reveal to what degree this so widely and uncritically accepted theory is indeed capable of explaining the perpetuation of contemporary undocumented inter-European migration. Data source for present contribution is an empirical research on undocumented Polish and Bulgarian migrants to in the period January 2004/October 2005. Presented arguments for and against the social capital theory, point at significant limitations to explain the migration under scrutiny. Relevant reasons for the weakness of the social capital theory are explored. The article concludes that the post-1989 undocumented migrations from Poland and Bulgaria to Belgium can be better understood and explained if several interacting factors are taken into consideration. These include the supply and demand factors as formulated by the classical push-pull theories of migration and a number of non-economic factors.
Keywords: Social Capital, Undocumented Migration, Polish Migrants, Bulgarian migrants, Social Networks.