In the course of planning, producing, deciding and implementing initiatives, programs and laws, i.e. the very process of policy-making, national parliaments and public administration are closely connected with each other. Ministerial officials prepare legislative proposals on behalf of the government, provide information about them for the parliament, defend them at the request of the parliament by handling parliamentary inquiries, and finally, implement valid law. Furthermore, Europeanization affects the balance of power between political and administrative actors. Public administration has become a dominating actor in the European policy cycle being extensively involved in drafting and implementing European law in the hundreds of comitology committees, and working groups associated with the Council and the Commission. Hence, for parliamentarians it seems to be more and more profitable to keep close contact with officials in order to stay informed. The paper is interested in which conditions cause interaction relations between these two groups of actors? Through integrating methods from both parliamentary and administration studies in Europeanization research we highlight four factors potentially accounting for legislative-executive relations in the member states: 1) mutual role perception, 2) administrative tradition, 3) relationship between government and opposition, and 4) the degree of Europeanization in policy fields. Our results come from a still ongoing comparative qualitative study at the German Research Institute for Public Administration Speyer. The paper bases on interviews with Swedish politicians and civil servants specialized in different policy-fields of EU policy-making.