Union density still varies considerably across Europe. This cross-national diversity has inspired multiple explanations ranging from institutional to workplace or socio-demographic factors. In this comparative multilevel analysis, we combine personal, workplace and macro-institutional explanations of union membership using the European Social Survey. By controlling for individual factors, we test the cross-national effect of meso- and macro-level variables, in particular workplace representation, establishment size, Ghent unemployment insurance and a society’s social capital. We conclude that all these institutional and social contextual factors matter in explaining differences in union membership.
