This article describes and analyzes a program of work in elementary mathematics teacher education at the University of Michigan that has, for a decade, been a site for the development of approaches to preparing beginning K-8 mathematics teachers that are both aimed at practice and centered in content. Among the products of this work are video records, instructional tasks, and assessments, as well as structures for collective work on our courses. These materials and ways of working comprise a collection of resources for both the systematic improvement of the knowledge base for teacher education and the professional development of teacher educators. This practice-based approach to the development of both our courses and their instructors has enabled us to improve professional instruction and to build knowledge that is useful beyond a particular course or the individuals who work in it. We begin by discussing 2 central problems of teacher education that our group has tried to address and then describe the types of materials and ways of working that we have developed. We analyze the features of the professional curriculum produced from this work, relate them to the problems, and consider issues about transferability to contexts beyond our own. (Contains 2 figures and 4 notes.)