The aim of this paper is to sketch a theoretical and methodological framework for analysing the influence of EU-membership on the political parties and party system of Sweden. The main point of departure is the theoretical framework for the Europeanization of national political parties developed by Robert Ladrech (2002). Although Peter Mair (2000) has depicted parties and party systems as relatively unaffected by European integration, Ladrech identifies several aspects where direct as well as indirect influence may take place: 1) policy/programmatic content, 2) organisation, 3) patterns of party competition, 4) party-government relations and 5) relations beyond the national party system. Consequently, the aim is more concretely to discuss the feasibility of a larger study of the Swedish parties (and party system) departing from Ladrech’s five dimensions. In a broader perspective, the ambition is to discuss the degree of which the Swedish party landscape has been affected by the EU-membership. Or in short: in which of Ladrech’s five dimensions can we identify a pattern of Europeanization?