This research has three main aims: firstly, to empirically analyse the determinants of different levels of integration by re-examining the evidence presented by Baier and Bergstrand (2004) in the JIE 64 (1); secondly, to analyse the importance of additional factors, in particular socio-political factors. Finally, to analyse the dynamics of the European Union integration process. The results show that although economic and geographical factors are the most important explanatory factors for the probability of regional integration agreement formation or enhancement, socio-political variables also contribute to explain the formation of regional integration agreements. Democracies and countries with a higher level of economic freedom are more likely to form or enhance RIAs.