This introduction to the special issue “Vermittlung in der internationalen Politik” (mediation in international politics) maps how the notion of “mediation” brings together recent research streams of IR theorizing that center on a relational understanding of international politics. It teases out the similarities between research projects that use concepts such as norms, practices, narratives, emotions, frames, and technologies to analyze international relations, and thus shows how “mediation” acts as a useful umbrella concept. The introduction charts the territory of a productive research agenda on “mediation” by distinguishing five research strands, which focus on an interactive understanding of agents and structure in the international order, and by discussing their specific understandings of “mediation” in the context of IR research: constructivist norm research, critical theory, practice theory, IO studies, and discourse analysis. A brief introduction to the papers in this special issue illustrates how they contribute to these research strands. Ultimately, this introduction underlines the conceptual and methodological potential “mediation” offers continuing relational IR research as well as for building bridges to other interdisciplinary research endeavors in the study of international politics.