This Chapter walks though the history of sustainable development in order to unveil its structure and inner workings. In doing so, this chapter shows how, through an iterative process in the United Nations General Assembly, sustainable development has been construed around three building blocks that are here referred to as the what, the how and the who. The what, referring to sustainable development as being integrated of a core of two principles—integration and inter and intragenerational equity, addresses the objective of sustainable development; the how, referring to the operational principles of sustainable development in its three environmental, social and economic dimensions, draws from principles that exist elsewhere in international law, and that allow for the implementation of the objective; the who, referring to the addressees of sustainable development, refers to the actors that are to implement sustainable development, which include but are not limited to, the State. This latter aspect highlights the transnational and global nature of sustainable development which, being conceived in the United Nations General Assembly, brings to its very centre the role of stakeholders, in particular businesses, for its achievement.