This Paper investigates the links between party organizations, the stability of party systems, and support for parliamentary democracy. The Paper starts from two widely accepted notions about developments in contemporary democracies: first that party “institutionalization” is an important part of the process of consolidating new democracies; and second, that the over-institutionalization of parties (“cartelization”) can pose different kinds of dangers to democratic stability, whereby unresponsive established parties generate pressures that erode democratic stability. Less dramatically, some have posited that the erosion of mass party organizations weakens popular support for established parties in ways that professional organizers cannot counterbalance. Building on measures of party institutionalization that were developed to study parties in emerging democracies, this paper explores relationships between party organizations and political stability in established democracies, drawing on half a century of party organizational data from the Katz-Mair Data Handbook and new data from the Political Party Database (PPDB).
