The Earth System Science Partnership of the four main global change research programmes has recently declared an 'urgent need' to develop 'strategies for Earth System management'. Yet what such strategies might be, how they could be developed, and how effective, efficient and equitable such strategies would be, remain unspecified. It is apparent that the institutions, organizations, and mechanisms by which humans currently govern their relationship with the natural environment and global biogeochemical systems are not only insufficient-they are also poorly understood. This lecture presents the science plan and implementation strategy of the Earth System Governance Project, a new ten-year global research effort developed under the auspices of the International Human Dimensions Programme on Global Environmental Change. The presentation elaborates upon the concept of earth system governance and on the central questions, methods and processes of a global research effort in this field. Earth system governance is defined as the interrelated and increasingly integrated system of formal and informal rules, rule-making systems, and actor-networks at all levels of human society (from local to global) that are set up to steer societies towards preventing, mitigating, and adapting to global and local environmental change and, in particular, earth system transformation. Based on this general notion, the science plan of the Earth System Governance Project is organized around five analytical problems that also stand at the centre of this presentation: The architecture of earth system governance; agency in earth system governance; the adaptiveness of earth system governance; problems of accountability and legitimacy of governance; and finally the question of access to goods and about their allocation.