Party membership, pre-parliamentary socialization and party cohesion

Party membership seems to lose relevance for political careers in many established democracies. Increasing numbers of parties are recruiting non-members as candidates. Yet, what are the implications of a lack of long-term party membership for party cohesion? In this paper, I argue that pre-parliamentary party membership is in fact crucial for cohesion. Using data from the Comparative Candidate Survey and voting behavior of ca. 2,000 MPs of the German Bundestag on free votes from 1953 to 2013, I examine the effect of length of previous party membership and the age of joining the party on indicators of party cohesion. Examining free votes allows for credibly controlling alternative explanations of unified voting behavior. Results are in line with expectations generated from social identity theory and underscore the importance of party membership for party cohesion. The paper concludes with a discussion on the findings' implications in light of recent developments in parties' candidate recruitment.