"What I like most about the this book is that it brings together in one study many aspects of research in mathematics education–it marries what we know about the meaningful learning of multiplicative structures with what we know about effective teacher training. It incorporates elements of the research base on what it takes to change teachers' beliefs and teaching practices. It is longitudinal and qualitative in nature—and thus gives some badly needed depth to this confluence of various areas of study in mathematics education." — Vicky L. Kouba, University at Albany, State University of New York"This book represents sound and important scholarship in the field of mathematics education, particularly in mathematics teacher education. The authors have conducted a good study, one that is of the long term nature that can serve as a model to be emulated by researchers and those interested in professional development." — Doug Jones, University of Kentucky