This publication contains a discussion of Michigan's Critical Materials Program and its continued development under a Toxic Substances Control Act cooperative agreement provided by the U.S. EPA. Information presented includes the need, authorization and development of a list of toxic substances of environmental concern, which in Michigan is the Critical Materials Register, and the utilization of the Register in Michigan as it applies to industrial discharges of wastewater. This information is intended to aid local, state, and federal governmental agencies in developing a program to evaluate the use and discharge of toxic substances. Although the scope of this report is designed to describe a system of evaluating the use and discharge of toxic substances by industrial wastewater dischargers, the program could be expanded or adapted to evaluate toxic substances discharges to the atmosphere or in solid waste disposal also. It is primarily directed toward governmental agencies that do not presently have a toxic substances evaluation program, however, it should also provide useful insights for those agencies that already have existing programs.