Europarties and the European Parliament (EP) political groups have decades of experience from constitutional reform processes. These partisan actors have influenced EU Treaty amendments while also proving inventive in designing new practices that have over time found their way into the Treaties. Drawing on interviews and parliamentary and party documents, this chapter explores the different avenues and strategies the three largest Europarties—European People’s Party, Party of European Socialists, Alliance of Liberals and Democrats for Europe—and their EP groups utilised for shaping the agenda of the Conference on the Future of Europe. It examines the distribution of power between Europarties and the EP groups and pays particular attention to dynamics inside the EP political groups, arguing that the agenda-setting stage of the Conference was strongly influenced by group leaders and other more senior, individual MEPs, many of whom are seasoned veterans of inter-institutional bargaining and EU constitutional development.