The UK Government has announced its intention to hold a referendum on UK membership of the EU by the end of 2017. This short report analyses the reform process that will now take place. The Government is right to press for a referendum as soon as possible in order to minimise uncertainty. Yet it must bear in mind the potential for delay and disruption in what will inevitably be a contentious process. The Government must also be mindful of the potential impact on the UK Presidency of the Council of the European Union in the second half of 2017. It would be highly undesirable to hold the referendum during the Presidency, and the Government must be ready to take contingency action if required. There is uncertainty over the specific roles to be played by key UK negotiators including the Prime Minister, the Foreign Secretary and the Chancellor of the Exchequer, as well as over how the internal Whitehall coordination process will work. The Government needs to explain not only how the negotiating process will operate from the UK point of view, but also how it will engage with key interlocutors in the EU institutions.