This chapter reviews various concepts of sustainability and provides distinctions between neo-classical economic and ecological paradigms of sustainability, welfare and economic growth. The development of a suitable framework has been hindered by persistent disjoints in public understanding of sustainability and by the different interpretations of optimal resource use from economic and ecological perspectives. Economics has produced two different views on sustainability, weak and strong. Weak sustainability asserts the substitutability of created capital and natural resources. This requires that the sum of natural and human capital must be non-declining. Strong sustainability, in contrast, assumes that created capital cannot substitute for natural resources, and it is the level of natural capital instead of the sum that must not decline. Next, neo-classical economic models and measures of sustainability are reviewed. In neo-classical economics, a properly measured, environmentally adjusted domestic product can serve as an indicator for sustainability. Ecological economics models and measures are also reviewed. For ecological economics, physical measures of ecosystem resilience and resource stocks, weighted against population and consumption pressure, can indicate sustainability. Finally, we describe some examples of multidisciplinary courses and a programme where these concepts have been taught at Nanyang Technological University in Singapore