This thesis analyses the extent to which particular electoral system features and rules affect the opportunities for, and proportionality of, the representation of certain far right and regionalist at various sub-national levels in key European Community member states. The thesis employs data provided in a unique data base at the University of Plymouth. This data includes a wealth of information concerning shares of the votes and shares of the seats for as many identifiable parties as possible in a range of sub-national elections in the post World War Two period and measures the proportionality of elections using three indices of proportionality. Various authors have previously attempted to identify which electoral features are primarily the cause of disproportionalty at the national electoral level. Within this thesis we will test their claims at various sub-national levels in several west European states. We will also assess the impact of these electoral features upon the representation opportunities of certain far right and regionalist parties, as we have examples of these parties being both 'small' and 'large' at the sub-national level.