Design for sustainability as an independent field of study is both multidisciplinary and cross-cutting. It encompasses engineering, the natural sciences, economics, finance, political science, the social sciences and the humanities. It concerns governments, corporations and consumers. Although these are not normally considered design topics, the effects of manufactured products and energy usage on society and the environment are increasingly impacting process design choices. Because of the numerous groups and constituencies involved, sustainability is a difficult concept to define. However, from a design perspective, professional competency in sustainability is becoming an important prerequisite for the production of economically viable products. Therefore, a comprehensive taxonomy of sustainable engineering and design is needed so that all those involved in this diverse field are fluent in the same concepts, even if their definitions of what sustainability means are different. This contribution will propose an outline for a sustainability taxonomy, including the key concepts that define professional competency in design and engineering for sustainability.