The routine finding of a positive relation between participation in voluntary associations and civic values and attitudes can be explained by two different causal mechanisms. On the one hand, some authors stress a process of self-selection: those who already have a more civic value pattern will be over-represented in voluntary associations, but their attitudes are not necessarily influenced by interaction within the associations (Stolle, 2001; Uslaner, 2002). Other authors emphasise socialisation effects: because of the interaction with like minded others, members of associations are imbued with more social and cooperative attitudes. In this view, associations function as ‘a learning school of democracy’ (Putnam, 1993; Hooghe, 2003).
While the socialisation approach seems to dominate the social capital literature (cfr. Putnam, 2000, 2002), the empirical research currently available does not fully support the assumption that associational involvement has strong socialisation effects. Although people who are members of associations are usually more trusting and tolerant, so far no one has convincingly demonstrated that social participation experiences have a strong independent effect on civic attitudes.