Security and defence issues have become increasingly important for the European Union. Whilst 9111 brought home the dangers of the new security threats, the Iraq war highlighted the divergences among the EU Member States concerning how to deal with them. When combined with the failings in the Balkans, the creation and development of the European Security and Defence Policy (ESDP) is particularly significant in shaping the EU's credibility in the international arena. However for ESDP to become more active, capable and coherent, the EU's Member States will need to reach agreement concerning when, where and how the EU uses force and to develop the necessary capabilities to fulfil their goals. Whilst academic attention has often been focused on the UK and France, this thesis offers a novel approach by examining the conceptions that Germany and Poland have of ESDP and the role(s) they want to play in developing the policy. It is argued that these two countries are central to the successful development of ESDP because due to their size, they should be taking on greater roles in its advancement. Continuity and change in Germany and Poland's roles, including their strategic culture will be highlighted which will act as a basis on which to analyse divergence and convergence between the two countries. This is of particular interest considering Poland's new membership status. Finally the convergence and divergence between German and Polish conceptions of security and defence issues will be placed in the context of the continuing development of ESDP and what impact this will have on the possible evolution of a European strategic culture.