Design for sustainability as an independent field of study is both multidisciplinary and cross-cutting. It encompasses engineering, natural science, economics, finance, political science, social science and the humanities. It concerns governments, corporations and consumers. Although 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. This contribution proposes an outline for a sustainability taxonomy, including the key concepts that define professional competency in design and engineering for sustainability. This contribution is an extended version of a paper originally published in the Proceedings of the 8th International Conference on the Foundations of Computer Aided Process Design Conference, Cle Elum, Washington, 2014. (c) 2015 Elsevier Ltd. All rights reserved.