This article reviews the by now extensive literature on the Europeanisation of the political systems of the EU-15, with an emphasis on parliaments and executives (i.e., governments and ministerial administrations). The Living Review highlights apparently contradictory effects of integration: de-parlamentarisation vs. re-parlamentarisation; bureaucratisation vs. politicisation; and centralisation vs. diffusion. These diverging assessments of the effects of integration do, in part, reflect diversity in the EU-15; in part, they are, however, also a result of differences in the specification of variables, research designs and theoretical approaches. Work that inquires into patterns of Europeanisation -across institutional domains, countries, regions and time -and which seeks to tackle the 'methodological nationalism' of the Europeanisation literature promises a clearer picture of the institutional consequences of European integration than we possess at present.This review is licensed under a Creative Commons Attribution-Non-Commercial-NoDerivs 2.0 Austria License. http://creativecommons.org/licenses/by-nc-nd/2.0/at/