9550081 Klanica Cherry Creek School District, in cooperation with school districts in Colorado and New Mexico and Metropolitan State College in Denver, prepares 144 mathematics teachers in eighteen secondary schools to teach the Interactive Mathematics Program (IMP) in grades 9-12. The five-year project provides direct and intensive support for all 144 mathematics teachers in those schools through a program of teacher enhancement that includes summer workshops (a three-week workshop prior to a teacher's first year of teaching IMP and a one-week workshop prior to each year s/he teaches a new level of IMP), quarterly Gatherings, and Immersion workshops. Participants meet with project staff weekly and have a daily professional development period for up to two years. At each of the schools, two teachers join the project in the first year. Two or more teachers per school are added each year, so that -- over a four-year period -- every mathematics teacher at the school will have been enhanced by the project. This experimental project provides significant opportunities for learning more about the critical issues involved in scaling up IMP implementation and how to make it cost-effective. The project includes significant evaluation, a leadership component, and production of professional development materials to assist others with teacher enhancement and implementation of IMP. Cost-sharing, which is 191% of the NSF award amount, is contributed primarily by school partners, with secondary cost-sharing from the National Interactive Mathematics Program, the Colorado Department of Education, U. S. West, and the Gates Foundation.