Although parliamentary government is generally taken to be party government and party cohesion is acknowledged a key element thereof, it seems an accepted part of comparative parliamentary research that the effectiveness of parliaments and the level ofparty cohesion are negatively related. This is in part a remnant of the Anglo-American comparative studies that have dominated the discipline for a long time. Within reactive parliaments, this negative relation fails to materialise. Combining results from earlier research and original data, it is demonstrated that a high level ofparty cohesion does not prevent parliaments to be an effective, independent player in government formation, the recruitment of cabinet ministers or policy making. Comparing ten European parliaments, the more effective parliaments do encompass parliamentary parties with the highest level ofcohesion. A more crucial element isperhaps the characteristic of parliamentary parties as essentially oriented to the extra-parliamentary party or as a dominant element in the party-as-a-whole. Further research is however necessary.