After elections, MEPs will most often join a political group or create new ones. These groups bring together MEPs from different Member States (http://www.europarl.europa.eu/meps/en/home) on the basis of their political affinities. Groups can also be formed at a later point in the parliamentary mandate. Currently there are seven political groups in the European Parliament.
A formally recognised political group must consist of at least 23 MEPs coming from at least one-quarter of the member states (i.e. seven, at least). MEPs may only belong to one political group while some do not belong to any political groups at all and are referred to as “non-attached” Members.
To set up a group, the President of the Parliament must be notified in a statement that specifies the group’s name, its members and its leadership.
In forming a group, MEPs accept political affinity by default and the Parliament does not usually assess political cohesion between group members. Only when it is refuted by MEPs concerned themselves, the Parliament will step in to evaluate whether a group has in fact been constituted in accordance with the rules.
Political groups can employ staff and are given offices funded through the Parliament's budget. The Parliament’s Bureau sets rules on how these funds and facilities are managed and audited. The funds made available to groups are intended to cover group staff administrative and operational costs, as well as expenses incurred due to EU-related political and information campaigns.
The budget may not be used to finance any form of European, national, regional or local electoral campaign or to finance political parties at national and European level or their dependent bodies.
Not all MEPs sit in groups. Those who do not, are called “non-attached" members. They also are entitled to staff and have rights under the rules set out by the Bureau.