Changing Conditions for Party Groups of the Swedish RiksdagIn this special issue of Statsvetenskaplig tidskrift, the intention is to study the cartelizationof the Swedish party system based on the party groups of the SwedishRiksdag. Especially if we investigate whether the parliamentary party groups havebecome increasingly similar from the late 20th century to the first decade of the 21th century. This purpose is treated in six distinct sub-studies designed to addressgaps in the theory of cartelization of political parties. Conditions for party changeare related to party finance, gender and medialization. The significance of theseconditions may be different, however, depending on the internal cultures of parliamentaryparty groups: some party cultures may impede while other may facilitatecartelization. Party change is analyzed through a study of the parties’ degree ofpoliticization along with a discussion of cartelization and political representation.