A large volume of fly ash is produced that does not meet current American Society for Testing and Materials (ASTM) specifications for use in the production of cement and concrete but could be used for other applications. In many cases, coal ash is required to meet ASTM specifications even when they are clearly inappropriate for the application (i.e., structural fill). Creating a classification system for fly ash that facilitates the use of performance-based specifications for use applications will broaden the utilization options for coal ash, resulting in elimination of disposal costs and opportunities for industry to develop new products and expand the use of coal ash in existing products. The inadequacy of the current classification system is one of the major technical barriers to increased coal by-product utilization. The goal of this project is to develop a classification system for fly ash that will provide a means of evaluating fly ash suitability for applications.