Most theories of legislative behaviour explain the behaviour of MPs through electoral incentives. However, they fail to explain variation in parliamentary activity when individual electoral incentives are largely absent. This article studies MPs’ activity in such a parliament: the Dutch Tweede Kamer. It examines four clusters of incentives that may drive parliamentarians to be active. Party and committee environments provide the best explanation for the level of activity of individual MPs. Reselection and promotion prospects explain MPs’ behaviour, but only under more particular specifications. Re-election prospects were not found to affect activity levels.