Encompassing the complex and multidimensional nature of environmental sustainability, this research attempts to answer three questions: What determines the level of environmental sustainability in national level analyses? How can the quality of governance be defined, measured and applied in the dynamics of political processes? And, how does the quality of governance influence the level of environmental sustainability? A proposed cross- national design shows how environmental sustainability is determined by quality of governance, level of democracy, annual economic growth rate, global economic integration and population growth rate. Conceptualizing governance and political software as institutional conditions for articulating the determinants of the level of environmental sustainability, this research argues that the quality of national governance is intrinsically related to, and even generates pressure for, environmental sustainability.