This chapter examines the difficulties that European integration has posed for the Conservatives under Cameron in the context of modernisation of the Conservative Party. It explores how two familiar problems, albeit in a new form, have reappeared and posed problems for Cameron’s modernisation project. First, the desire of EU Member States to pursue further integration has limited UK influence and second, Conservative divisions have returned with a vengeance, this time between soft Eurosceptics supporting membership of a reformed EU and hard Eurosceptics seeking fundamental renegotiation or withdrawal. The chapter also assesses an important new dimension to Conservative difficulties on the EU issue, namely the rise of UKIP. It looks at the challenge it poses and the Conservative response. The chapter concludes by considering how the EU issue may play out in the post-2015 general election period.