The paper discusses a new U.S. strategy to reduce public exposure to toxic air pollutants in the ambient air. The strategy calls for state and local authorities to take on more of the lead regulatory role. The shift in emphasis and responsibility prompted EPA's Offices of Research and Development (ORD) and Air Quality Planning and Standards (OAQPS) to develop and implement an innovative technical assistance program, called the Control Technology Center (CTC). It has since been expanded to include technical assistance in the areas of control of air toxics, particulate matter, and volatile organic compounds (VOCs); emission measurements; and other areas where expertise is available to ORD and OAQPS. Available through the CTC are three categories of technical assistance: telephone HOTLINE calls, direct engineering assistance, and technical guidance projects. The CTC HOTLINE is a special telephone number that state and local agencies can call for easy access to EPA personnel who can provide prompt assistance. Engineering assistance projects require more in-depth engineering analysis; these projects are short-term (less than 3 months) and specific in nature. Technical guidance projects result from problems identified by more than one agency; they are longer-term and of national interest. The paper discusses five CTC projects to illustrate the assistance provided.