For decades, actorness has been a much‐debated concept central to the theorization and analysis of the EU's evolution as an international actor. While this concept is often presented as a set of factors, which together shape the EU's capacity to act internationally, the literature displays a surprisingly deficient understanding of how these factors interact in the emergence of actorness. To address this gap, this article theorizes about actorness from an interactionist role theory perspective, which draws on the works of social psychologist George Herbert Mead. In building on this perspective, the article conceptualizes actorness as an entity's capacity to (re)‐imagine and realize roles for its ‘self’ in (specific contexts of) international affairs. This capacity, the approach suggests, emerges in the interplay of (social and material) resources, creative action and (domestic and external) role expectations.