This article examines the effect of country size on the professionalization of politicians in six European micro-states and a large-scale democracy – Germany – since 1980. The article revisits an ongoing debate about the extent to which either country size or government size are causal factors in the individual professionalization process. Using an original dataset consisting of 6,940 parliamentary mandates – 2,809 individuals – in national parliaments, the article shows that country size is a determinant of the degree of politicians' professionalization. The article further demonstrates that political parties' gatekeeper role is the key causal mechanism explaining the influence of population size on politicians' professionalization.
