Agency is one of five core analytical problems in the Earth System Governance (ESG) Project’s research framework, which offers a unique approach to the study of environmental governance. − Agency in Earth System Governance draws lessons from ESG–Agency research through a systematic review of 322 peer-reviewed journal articles published between 2008 and 2016 and contained in the ESG–Agency Harvesting Database.− ESG–Agency research draws on diverse disciplinary perspectives with distinct clusters of scholars rooted in the fields of global environmental politics, policy studies, and socio-ecological systems. − Collectively, the chapters in Agency in Earth System Governance provide an accessible synthesis of some of the field’s major questions and debates and a state-of-the-art understanding of how diverse actors engage with and exercise authority in environmental governance.