This forum explores continuities and transformations in the way Europeans thought about integrating their continent politically, economically and ideologically across the twentieth century. It questions the idea of a Stunde Null, which sees European integration primarily as a response to the destruction of the Second World War. Instead, the forum shows how mentalities, ideologies, challenges and constraints that arose before 1945 shaped the way European elites conceptualised and pursued unification in the post-war decades. The European leaders who orchestrated integration after 1945 were looking both backward and forward, trying to revive older visions for a unified continent and overcome long-standing problems while simultaneously aspiring to a new, supranational regional order that would preserve Europe's position as a global power. In exploring such continuities, this forum adds a regionalist dimension to the burgeoning literature – by Patricia Clavin, Daniel Gorman, Mark Mazower and others – on the connections between interwar internationalism and the post-1945 global order, and on the continuity of intellectuals, experts and politicians through the middle half of the twentieth century.