The work examines the role that is Parliament's due in the exercise of the function of control over budgetary policies. To that end, the authors set out from an examination of the nature of the Constitution of the European Union and of those of the Member States, giving an account of the reasons that have induced the European system to involve the national parliaments in its decision-making processes. Specific attention is then given to an analysis of the rules concerning the function of control of the Italian Parliament in the matter of public finance and of European policy of the Government, introduced by Constitutional Law No. 1/2012 and by Law No. 234/2012. The conclusive part is devoted to analysing the potentialities and difficulties implicit in the instruments proper to interparliamentary cooperation in the exercise of the functions of control over budgetary policies, with particular reference to the vicissitudes of the Interparliamentary Conference instituted by Art. 13 of the Fiscal Compact for the purpose of guaranteeing the participation of the national parliaments in the economic and financial governance of the economic and monetary Union.