Most MEPs belong to one of the parliament's political groups. None has an overall majority, so amendments need the support of more than one group to get through. On most issues the parliament divides along classic left-right lines.
A group must have at least 19 members, from at least five member states. The larger the group, the more funding it receives, the more key committee posts it gets and the longer it can speak in debates.
Some groups are broad churches: the EPP-ED includes euro-enthusiast Christian Democrats and eurosceptic British Conservatives while the UEN includes the moderate Irish Fianna Fail party and Italy's post-fascist National Alliance.
PARLIAMENTARY GROUP WEBSITES:
The BBC is not responsible for the content of external internet sites