The European Green Party is a transnational political party having as its members Green parties from European countries (although not necessarily from European Union member states). Parties can also become observers. Since 2004 individual membership of the European Green Party is also possible.

The most important bodies of the EGP are the Congress, the Council and the Committee.

• The Congress consists out of 400 representatives of member parties and Green MEPs. These are allotted proportionally on basis of their votes in the most recent European or national election. Each party has at least four members. The Congress has the last word on general policy of the EGP and its guiding principles.
• The Council is made up of representatives of the MEPs and the member parties. It is responsible for political affairs between congresses and it decides over organizational matters, such as the election of committee, the application of members and observers and the statutes of the EGP.
• The Committee consists of nine members elected by the member parties, including two spokespersons (one man and one woman), a secretary-general and a treasurer as well as a delegate of the Federation or Young European Greens (FYEG). They are responsible for daily political affairs, the execution of the council's decisions and the activities of the secretariat-general.

The member parties also form regional networks such as Green Islands Network ("a network for Green Parties in Britain, Ireland and associated islands"), the Baltic Sea Greens, the Green Mediterranean Network, Green Adriatic Network and the North Sea Greens. Working Groups are also formed of persons nominated by the parties to address specific policy issues and to present policy papers for approval by the Council.