This two-year project will enable twenty professional development teams from around the country to improve the teaching of middle school mathematics in their home school districts. During the first summer, the teams will participate in a three-week workshop in which they will familiarize themselves with outstanding instructional materials, study the history of mathematics, and develop plans for curriculum reform in their own schools. Materials to be examined for possible inclusion in the curriculum include the Middle Grades Mathematics Project (Michigan State University), the Mathematics Resource Project (University of Oregon), the Quantitative Literacy Project (American Statistical Association and NCTM), the Harvard Middle School Mathematics Project, Estimation in a Modern Society (University of Missouri), Math and the Mind's Eye (Math Learning Center), and Getting Ready for Algebra (Ohio State University). Academic-year activities include visits to the participants' schools by the project staff and written reports from the development teams. During the second summer, the teams will return for a two-week follow-up workshop to discuss their experiences in implementation and to share ideas. A book documenting the results of the project will be produced. The school districts will contribute an amount equal to 42% of the NSF award as cost-sharing.