The University of Northern Iowa seeks funds for a three-year program to improve the teaching of secondary school mathematics through implementation of the NCTM Standards and the use of the Addenda materials. Forty-two Presidential Awardee middle and high school mathematics teachers will receive three weeks of intensive summer training in effective in-service skills and in algebraic thinking and its connections to various areas of mathematics. They will then conduct 12-hour in- service programs in their local school districts during the school year. The second year participants will attend a two-week summer program, followed by their presenting one-week regional summer workshops and 12-hour regional and state in-service programs. The third year participants will attend a one-week summer program and will present one-week summer workshops. Follow-up activities will include field-testing of materials developed for the workshops and regional meetings held during the school years. The project will include in- service packets, a monograph on evaluation methods, and a paper summarizing research on teacher change, all of which will be prepared by participants and staff. In addition to the forty-two first-wave teachers, it is anticipated that 1680 second-wave middle and high school teachers will be enhanced. The dissemination of the in- service packets has potential to create a third-wave of teacher enhancement. The University of Northern Iowa's cost-sharing will account for 13% of the NSF budget. This model delivery system for in-service training has high potential for becoming an exemplary teacher-teaching-teachers model which could serve as a guide for other mathematics teacher enhancement programs.