The Educational Leaders in Mathematics (ELM) Project, was an experimental inservice program for teachers of mathematics, grades kindergarten to 12. The major focus on the project was to help teachers develop and implement approaches to mathematics instruction based on a constructivist view of learning. ELM demonstrated the significant impact of combining constructivist summer inservice institutes with intensive, ongoing follow-up support. Teachers not only integrated into their instruction new strategies, but also showed evidence of having developed constructivist views of mathematics learning as a basis for their instructional decisions. Students attitude scores and teachers observations reflected improvements in students' attitudes about, conceptions of, and communication in mathematics as well as in problem solving and conceptual understanding. ELM demonstrated that teachers can make student understanding and problem solving high priority and decrease emphasis on computational skills without a drop of in tests results. This monograph describes the ELM Project's philosophical basis and methodology, and presents the instrumentation results, and conclusions in detail. A bibliography is included, and questionnaires and student attitude surveys are appended. (Author/JD)