Publisher’s description: This volume addresses the “who" question of mathematics teacher education. The authors focus on the various kinds of participants in mathematics teacher education, professional development and reform initiatives. The volume consists of six sections. The first two sections are on individual mathematics teachers and teams of mathematics teachers as learners, both containing a separate chapter dedicated to prospective and practising teachers. The third section puts an emphasis on communities and networks of mathematics teachers as learners. One chapter focuses on face-to-face learning communities of prospective mathematics teachers, whereas another chapter does the same for practising mathematics teachers. Two further chapters in this section deal with virtual communities and networks of prospective and practising mathematics teachers, respectively. The fourth section shows a shift of focus to the development of schools, regions and nations as a means of improving mathematics teaching and learning. The fifth section puts an emphasis on the use of action research in mathematics teacher education, on the collaboration between teachers and didacticians, and on the mathematics teaching profession in general. Lastly, the sixth section presents a “critical response" to the whole volume from two specific perspectives: One chapter sifts out interesting issues and indicates the complexity and diversity of the field and the variety of contributions, approaches, theoretical and practical stances in this volume, and the last chapter offers a theoretical perspective on fundamental problems in the context of investigating the communication issues raised. These two chapters form a reflective closure of the whole volume. The articles of this volume will not be indexed individually.