This paper investigates the impact of associational membership on anti-immigrant attitudes and extreme right voting. It provides a unique test of this relationship by considering jointly direct individual membership to various types of association as well as the density of these social networks in the individuals’ environment. In contrast with previous research, the results show that the role of social capital is weaker than hypothesized. Using the PIOP-ISPO post electoral surveys of 1999 and 2003, we show that the intensity of public social life in the environment has no significant effect on attitudes and behaviour, and individual social capital has a differentiated effect depending on the nature of the association individuals belong to. Membership to political associations has an effect on both extreme right voting and on negative attitudes toward migrants. Membership to non-political organizations has no impact on voting behaviour but is negatively correlated with anti-immigrant attitudes. In sum, the study emphasizes that the influence of social capital is much less straightforward than assumed in most of the literature.