Since the ratification of the Maastricht Treaty, the EU has seen a dramatic increase in the use of various mechanisms of differentiation, be it temporal, territorial or functional. As of today, more than fifty percent of EU policies have been affected by differentiation. While much of the existing literature on differentiated integration has focused on the supply side of differentiation, little attention has been paid to the demand for differentiation. Based on party manifesto and Eurobarometer analysis, this chapter attempts to fill a gap in the literature by focusing on two domestic actors that shape demand for differentiation, namely political parties and public opinion. It is argued that given the saliency of this issue, party positions on European integration are now best measured through the lens of preferences on differentiation, per policy area. The chapter further demonstrates that even more needs to be done to analyze how citizens understand the causes and effects of differentiated integration; countries that experience differentiation as a result of referendums tend to display the strongest support for national decision-making in various policy areas.