Anti-immig ra tion parties have emerged in most Western demo cra cies and in some coun tries have enjoyed consid er able elect oral success. Many schol ars have studied the factors underly ing the elect oral perform ance of these parties because it is these parties that affect real-life policy outcomes in their coun tries (e.g. Golder, 2003; Ivarsflaten, 2008; Van der Brug et al., 2005). Electoral success does not auto mat ic ally trans late into policy influ ence, however, so the ques tion concerns the extent to which the policy influ ence of anti-immig ra tion parties is related to their elect oral fortunes. Needless to say, the elect oral perform ance of anti-immig ra tion parties has an impact on

the direct policy influ ence they can exer cise in parlia ment and, if they gain access to power, in office (see Heinisch, 2003). Anti-immig ra tion parties’ elect oral success might also exert indir ect effects, i.e. by influ en cing other parties’ policy posi tions (see also Williams, 2006: 51). To what extent is this the case? Do elect oral pres sures from anti-immig ra tion parties exert ‘conta gion effects’1 on the posi tions of other parties on the issues that they try to mobil ize on, most notably, immig ra tion? This is the main ques tion guiding my article. This ques tion is seldom addressed, which is perhaps surpris ing as the answers are

inter est ing from a scientific perspect ive. The extent to which anti-immig ra tion parties affect party compet i tion is a relev ant ques tion in several research fields. Moreover, its import ance goes beyond scientific interest. If such conta gion effects exist, then the pres ence of antiimmig ra tion parties would affect policy-making through out Western Europe, which would raise all kinds of ques tions about the desirab il ity of this situ ation. Here, I focus on a key issue of anti-immig ra tion parties, namely immig ra tion policy. I

assess whether the elect oral success of anti-immig ra tion parties has any effect on the posi tions of the other parties in contem por ary Western European coun tries regard ing immig ra tion, and, if so, what it is. I focus on one type of impact, defined in terms of Downsian spatial compet i tion. An effect is considered ‘conta gion’ if other parties shift to more restrict ive immig ra tion policy posi tions after elect oral success of the anti-immig ra tion party in their country. I measure conta gion effects in various ways, not only concern ing right-wing parties – compare with the ‘conta gion of the right thesis’ (e.g. Norris, 2005) – but also conta gion affect ing the party system as a whole.