With a focus on collaboration and resistance against Fascism/Nazism in the 190s and 1940s, this special issue addresses a topic that has drawn a lot of scholarly attention, but is most commonly discussed in nation-centric debates. Within those debates, collaboration is often considered a betrayal of national ideals while resistance is seen to affirm them. Both resistance and collaboration, however, had transnational dimensions which reflected the international reach of communism and fascism and the destruction of many nation-states in the wartime period. Collectively, the essays in this special issue indicate new ways of approaching the complex topics of resistance and collaboration in the age of the Second World War. Without suggesting that this is the only way of thinking about both subjects, we hope that these approaches will further enrich what has become a much more open-ended discussion about some of the most contested aspects of that war.