Party Membership Role and Party Cartelization in Belgium and Italy: Two Faces of the Same Medal? GIULIA SANDRI Université Libre de Bruxelles TEUN PAUWELS Université Libre de Bruxelles The cartel party model has triggered a burgeoning literature on its theoretical implications, and has been largely tested empirically. Nevertheless, the dimension of the model that concern the relationship between members and elites has been rather neglected, even though the membership role variables are the sole features of the cartel party that transcend the simple intensification of the previous catch-all model and that carry the most extensive explanatory power. This article explores the role of party membership and activism in contemporary parties in two West European party systems to assess in a quantitative way the applicability of the cartel party theory. We explore the relationship between party ideology and the degree of cartelization. By examining the relationship between all these different dimensions, we challenge the idea that a retrenched membership role and cartelization are linked processes. Keywords: Political Parties, Party Internal Organization, Cartel Party, Party Membership, Parties in Western Europe. El modelo de partido de cartel ha disparado una floreciente literatura sobre sus implicaciones teóricas y ha sido ampliamente probado empíricamente. Sin embargo, la dimensión del modelo que concierne a la relación entre los miembros y las elites ha sido descuidada, aun Acknowledgements: Earlier versions of this article have been presented at the Conference on Party Membership in Brussels (2008) and the Annual European Graduate Conference on Political Parties in Birmingham (2009). The authors would like to thank the participants for their comments. We are also grateful to Stefaan Walgrave, Pascal Delwit, Riccardo Pelizzo, the reviewers, and editor of this journal for their many suggestions. The research for this article was made possible by the generous support of the Belgian science policy (Interuniversity Attraction Pole on Participation and Representation, http://www.partirep.eu). Politics & Policy, Volume 38, No. 6 (2010): 1237-1266. Published by Wiley Periodicals, Inc. © The Policy Studies Organization. All rights reserved.