The European Union (EU) has experienced significant changes over the last few years. The EU has enlarged from 15 to 25 members and has been working to implement a new constitutional treaty to institute internal reforms and further political integration. The EU has also taken steps toward developing a common foreign policy and defense arm. This report describes the current status of the EU's constitutional treaty, EU enlargement, the EU's evolving foreign and defense policies, and possible implications for U.S.-EU relations. It will be updated as events warrant. For more information, see CRS Report RS21372, The European Union: Questions and Answers.