Unlike studies of the way legislation is made, parliamentary control acrossmultiple government systems – i.e. ‘cross-parliamentary control’ – has not yetreceived systematic consideration. By cross-parliamentary control, I refer tosituations where a parliamentarian uses parliamentary control tools of onegovernment system to control the government in another. Based on theliterature on classical single-level control, previous studies of the questionactivities carried out in the European Parliament, and an explorative casestudy of cross-parliamentary control within the Danish Realm, this paperhighlights the potential prevalence of this unexplored phenomenon. Finally,it sets forth four theses for how multi-level legislative control is prone tomanifest itself in other contexts.