The National Council of Teachers of Mathematics published their vision of active, problem-centered instruction with a goal of conceptual understanding in 1989. Fifteen years after these reforms were proposed the changes are reflected in school policy and elementary mathematics curriculum, but only limited change has actually occurred in classroom instruction. With the belief that the classroom teacher is the key person affecting educational change, this case study examines the journey of five elementary classroom teachers as they transformed their mathematics instruction from traditional to reform-based, with the purpose of identifying the key elements that influenced the changes. This is a multi-case study involving five elementary classroom teachers who have recently been the recipient of the Elementary Presidential Award for Excellence in Teaching Mathematics. All of these teachers began teaching with traditional textbook programs and have changed their teaching to reform-based, problem-centered instruction. Over the course of two one-hour interviews each teacher told the story of his or her changes, explaining the influences, the key resources, the influential people, and the support they received in the process. The cases are individually presented; then all five are examined together in a cross-case analysis using a constructivist theoretical perspective. Three key elements were found to be influential in the teachers' change journeys. First, all five were self-motivated to make changes in their mathematics instruction. They were looking for practices that would give their students both better understanding and positive dispositions. All believed the reform-based instruction met these goals. Second, all five engaged in rich professional discussions about the changes they were making. These discussions were in groups with high levels of trust, in which the teachers freely shared concerns and successes, asked questions, and compared experiences. They were learning communities that supported the teachers' development of pedagogy and knowledge, allowing them to become confident practitioners. Finally, all five teachers were passionate about their teaching. The learning of their students and the improvement of their teaching were the prime considerations in the changes they adopted and the knowledge and skills they developed. / Graduation date: 2004