Much of the empirical literature on party membership has focused on longitudinal trends in aggregate country-level membership figures. A recurrent conclusion of these studies has been party membership decline. Framed within the context of theoretical debates on party decline and erosion of conventional political participation, the decline in party membership figures has been considered as an evidence of a decreasing influence of political parties on citizens’ behaviour. These studies bring forward systemic institutional or structural explanations for this decline. However, when disaggregating the figures, at the party level, the trends are far less linear, which calls for other explanatory factors of membership fluctuations.
This paper aims at testing alternative explanations for membership fluctuations, including short-term factors (electoral cycles) and party-level factors (party age, party family, party organizational features). In order to do so, the paper relies on an original dataset on longitudinal, yearly-based party membership figures in 25 countries.
