The continuous increase in the number and size of urban regions across the world pose great challenges for sustainable development. Given the connection between energy use, greenhouse gas emissions and climate change and the reality that the built environment emits around half of total emissions, the construction industry has considerable potential to reduce emissions and a key role in mitigating global warming. Other local challenges include for example loss of species and habitats, social degradation of neighborhoods, and an overall erosion of sustainability. Urbanisation patterns and the lifestyles of urban dwellers also affect the planet on wider scales and contribute to shaping bio-physical processes on planetary scales and affect how humans mentally connect with the Biosphere. However there is evidence our current understanding of the concept of sustainability, and thus sustainable development, is fragmented and unclear. There are a plethora of terms used to cover sustainable buildings, such as ecological, green, Gaian, zero energy, eco-friendly and environmental; all of which come in, and out, of fashion over time; do they mean the same thing or are they different? Furthermore, do the stakeholders within the built environment demonstrate a clear understanding of the concept of sustainability or; are they muddled and confused? The consequence of unclear thinking and a lack of understanding is that ultimately the built environment stakeholders are unlikely to deliver ‘sustainability’ efficiently or even at all, with the broader and more onerous consequences for society as a whole. In addition what are the implications for education and should academics be broadening the debate? This lecture examines the environmental, economic, social, political and philosophical thinking underpinning the concept of sustainable development and shows how different perspectives reflect very different ways of thinking about sustainability and sustainable development. It aims to create a better understanding while offering creative solutions.