The European Commission (Commission) is the the executive branch of the European Union, it manages and runs it. The Commission is assisted by a civil service made up of 46 Directorates General (DG's) and services, which are mainly based in Brussels and Luxembourg. The Commission enjoys a substantial degree of independence in exercising its powers. Its job is to uphold the common interest, which means that it must not take instructions from any national EU government. As the EU’s executive arm, the Commission implements the decisions taken by the Council of Ministers in areas such as the common agricultural policy. It has wide powers to manage the EU’s common policies, such as research and technology, overseas aid, regional development, etc. It also manages the budget for these policies. Its principal power is that it has the monopoly of the proposal of all EU laws. It doesn’t make the laws, it proposes them to the Council of Ministers on the basis of the European treaties. So every law in the EU starts as a Commission proposal. As ‘Guardian of the Treaties’, it has to ensure that the regulations and directives adopted by the Council of Ministers and the European Parliament (Parliament) are being implemented in the member states. If they are not, the Commission can take the offending party to the Court of Justice to oblige it to comply with EU law.

Since 2004, the Commission has been made up of one Commissioner from each member state. Its members are appointed (not elected) for a five-year term by agreement between the member states, subject to approval by the Parliament. Commissioners take an oath to represent the Commission, not their own country. Thus Commissioners are bound to represent the interests of the EU as a whole rather than their home state. The Commission is answerable to the Parliament, and the entire Commission has to resign if the Parliament passes a motion of censure against it.

The President of the European Commission is the most powerful office in the EU. As the head of the Commission, the President is responsible for allocating portfolios to members of the Commission and can reshuffle or fire them if needed. He determines the Commission's policy agenda and all the legislative proposals it produces. The post was established in 1957 and is appointed by the European Council and Parliamen for five year terms. Once elected, he, along with his Commission, is responsible to Parliament which can censure him. The current President is José Manuel Barroso, who took office in October 2004. He is a member of the European People's Party and is the former Prime Minister of Portugal. Barroso is the eleventh President and has a mandate until the end of 2009.