This dissertation analyses the consequences of seemingly placeless processes like the European integration and the increasing economic globalisation on Brussels and the people living there. The study shows that Brussels has become one of our time's most important international political capitals and a leading business node in Europe. European institutions, international organisations, headquarters and subsidiaries of transnational corporations are increasingly locating themselves in Brussels. Simultaneously there has been an influx of transnational professionals working in the international sector. This research shows that with the internationalisation of Brussels there has been concomitant economic restructuring with the emergence of an advanced service economy. The labour market has become polarised between those who have jobs and those who do not. Brussels has also experienced a spatial and socio-economic polarisation along ethnic lines. The thesis explores the connections between these changes and Brussels' international role. Drawing on the world / global city thesis of Saskia Sassen and John Friedmann, a theoretical framework is developed to analyse this. One of the important results of this study is that the world / global city thesis needs to be complemented with a thorough analysis of the place: the political and historical context, and also the role of the local agents, to enable an explanation of the observed development. The interplay between global and local processes needs to be clarified. It is also argued that to properly understand cities with an international role like Brussels, we need to know why international agents locate there. Michael Storper's concepts of 'economic reflexivity' and 'territorial specificities' are used to analyse the rise of Brussels into a reflexive world city - a city vibrating with specific knowledge, produced through inter alia social interaction and critical reflection, that some transnational agents find extremely vital to tap into.