The literature on the policy-making of the European Union (EU) has trouble understanding the long-term evolution of EU policies. While numerous accounts exist that analyze EU policies from a historical, analytical-descriptive and normative perspective, no existing account has studied the evolution of EU policy output from a positive perspective. This thesis wants to start filling this gap in the literature by studying the patterns of policy evolution in the European Union’s research and technology development (RTD) policy. This policy is studied at three different levels of analysis. The first level is that of budgetary dynamics; here I test two alternative hypotheses on the pattern of budgetary change, both derived from the American literature: the classical incrementalist hypothesis, and the punctuated-equilibrium hypothesis of Bryan Jones and Frank Baumgartner. The second level of analysis is that of agenda dynamics, where I study the pattern of issue expansion/contraction on the fragmented agenda of the EU, and test two alternative hypotheses on the allocation of agenda space to RTD policy. The third level of analysis is that of institutional dynamics; here I test the hypothesis that institutional stability is associated with phases of incremental changes, whereas institutional developments occur in correspondence with budgetary punctuations. The empirical results show that both the budgetary and agenda dynamics of this policy are fully compatible with the punctuated-equilibrium hypothesis. However, the hypothesis on the correspondence between budgetary punctuations and institutional change is to be rejected. The final part of this work investigates the mechanism and the necessary conditions for the emergence of new policy priorities, by focusing on the recent emergence of security RTD as a new priority of the Framework Programme. This dissertation is the first work to empirically test the punctuated-equilibrium model on the EU, with an extensive and original dataset composed of budgetary, agenda and institutional delegation data.