This Introduction seeks to provide a foundation from which readers can delve into the following chapters of the volume. I begin with how the concept ‘anthropocene’ has found its way into international environmental and climate change policy discourse. Next, some conceptual clarity is pursued by way of a comprehensive review of how the ‘anthropocene’ has featured in the academic literature. The difficulties in doing so should become apparent. A survey of the multiple ‘anthropocene’ discourses attests to the contested nature of the term, as does acknowledgment of the multiple alternative neologisms which have been used in its place. As a collective endeavor, the principal orientation of the volume is then set out, along with its rationale and relevance for the field of International Relations (IR). Ultimately, the case is made for ‘ontopolitics’ as a fruitful and necessary lens through which to approach the manifold framings of the ‘anthropocene’. To assist the reader in navigating the volume a brief synopsis of the constituent chapters is provided, outlining some of their key features.