The interdependency of socio-ecological systems and the increased reach of human activity have led to major political and scientific challenges in the governance of environmental resources. This chapter reviews the state of our knowledge on the matter. The chapter begins by discussing the specificity of global environmental challenges. Then it discusses three main issues. First, the chapter addresses the question of the optimal level of governance given that environmental goods have wide variation in scope and can be produced according to various aggregation technologies. Second, the chapter argues that the design of governance instruments and regulation should be based on a relevant conception of human motivation and rationality. Third, the chapter revisits the governance toolbox and considers benefits and costs of alternative modes of governing. The chapter concludes by discussing the potential of polycentric and networked governance as well as the need for more integration at the global level.