To meet the goals of sustainability and to enable industrial ecology, green chemistry and engineering needs to be studied from a life-cycle perspective. When designed correctly, green chemistry and engineering can affect multiple stages of the life cycle of a product or process. Successful implementations of green chemistry and engineering research are improving the environmental impacts of chemical products and processes in every stage of the life cycle while also offering economic incentives. Analysis of new and existing green chemistry and engineering technologies with quantitative and qualitative metrics can identify and quantify these benefits. The examples presented illustrate the principles of life-cycle assessment as applied to green chemistry and engineering.