What is the place of infrastructures in understanding the post-Cold War political transition in Central and Eastern Europe (CEE)? This chapter uses the lens of infrastructure to investigate the (re-)positioning of state identity in international politics, focusing on refashioning of the Czech Republic as a “new European”. It suggests that (security) infrastructures have co-produced the political transition, since their reworking has helped envision, design, assemble, and thus also give concrete meaning to becoming a new and valued member of Europe. The chapter demonstrates this dynamic in two vignettes: biosecurity expertise and biodefence research. It shows that the Czech biosecurity infrastructures draw on expertise and technology developed in past times, and these are updated and repurposed to fit the vision of modern, technologically advanced Western security politics. The chapter concludes by arguing for greater attentiveness to how political transitions are made via a broader scope of actors, practices, and institutions, which are enrolled into the project of repositioning national identity.