Institutional structures and decision-making processes, which have been established in the European Union, fall beyond the scope of national rules for the functioning of parliamentary government. National parliaments of the EU member states have not succeeded in acquiring solid positions in the multilevel constellation within the Union. Yet nowadays they are assigned an important mission in their efforts to overcome, alongside the European Parliament (EP), the growing democratic deficit at both the European and national levels. The article is meant to assess the potential of national parliaments in capitalizing on the Lisbon Treaty provisions and on new forms of their engagement with supranational institutions (the European Council, the European Commission and the EP in particular), aimed at enhancing their legitimizing influence. General paradigm for the analysis is determined by the multilevel governance concept (MLG). It allows for a picture of European decision-making, which is shared by actors placed at different levels of the governance structure. National parliaments are supposed to be provided with multiple access points to the political process in the European Union as well. But the MLG vision doesn't contradict the fact that the key role within the EU belongs to those who occupy the highest executive power positions at the national level. Three directions for the national parliaments to intensify their involvement are put into spotlight: parliamentary control over national executives; control of compliance with the subsidiarity principle in European legislative proposals and supranational decisions; political dialogue with the European Commission and interparliamentary cooperation. The analysis proves that conditions are ripe for more active stance of national parliaments in the EU affairs. The “system of early warning” of the subsidiarity principle violations, provided for in the Lisbon Treaty, seems most promising. But national parliaments themselves will still have to demonstrate more persistence when using new instruments.