The major theme of the 21st International Symposium on Chemical Reaction Engineering (ISCRE 21) is sustainable development. Many of the critical sustainable development challenges revolve around: energy, resources, food, water, and environment. Successful developments require sustainable resource-use strategies, processes, products, and services. In addition, the major challenges that we face are long-term, massive in scale, and have high future uncertainty. Sustainable developments must work now, work in the future, not put off addressing the problem, and not disadvantage future generations. These are tall challenges. Sustainability in research, development, and demonstration (RD&D) faces these same challenges and must fit into a similar framework. CRE is an important activity contributing to all aspects of RD&D. Sustainable RD&D supports both short-term and long-term needs, provides for a broad range of options, and continuously evolves to address progress made and shifts in future needs. Sustainable RD&D must provide society and/or business a portfolio of technology options and develop the science and technology base to support their application, to seed future discoveries, and to address uncertainty. This cannot be done at the individual level but must occur at the organizational level to be truly sustainable. Approaches to achieving this are illustrated with examples of success and failure from the health, semiconductor, energy, and transportation areas.