Tracy HelliwellTracy Helliwell is an associate professor of mathematics teacher education at the University of Bristol, United Kingdom. Her research interests include mathematics teacher education and professional development; mathematics teacher learning and identity; curriculum design in school mathematics; mathematics teaching for sustainable futures; and mathematics teacher educator learning and expertise. She is currently an associate editor of the journal For the Learning of Mathematics.  Sean ChorneySean Chorney is an associate professor of mathematics education at Simon Fraser University in Burnaby, Canada. His research interests include mathematising social and ecological issues, the use of digital technology in learning mathematics, and exploring the expertise of MTEs. He is an associate editor of the International Journal of Science and Mathematics Education and the senior editor of Vector, the teacher journal of British Columbia, Canada.Olive ChapmanOlive Chapman is a professor in mathematics education at the University of Calgary, Canada. Her research interests include mathematics teacher thinking, practical knowledge and learning; mathematics and problem solving knowledge for teaching;  and mathematics teacher educator knowledge and learning. Her past professional service include Editor-in-Chief of the Journal of Mathematics Teacher Education and member of the Board of Directors of the National Council of Teachers of Mathematics.

• Chapter 1. Introduction to mathematics teacher educator's expertise: Experiences, conceptions, Learning and development.- Part 1: Conceptions of MTEs’ expertise in the context of practice: Chapter 2. The role of mathematics teacher educators in re-organising prospective teachers’ mathematics for teaching.- Chapter 3. The work of mathematics teaching practice teachers: a case study of initial mathematics teacher training in Uruguay.- Chapter 4. Hubs and threads: Steering between metaphors towards a representation of a mathematics teacher educator course design.- Chapter 5. Student-Adaptive Pedagogy: A Development Model for Preservice Mathematics Teachers.- Chapter 6. MTEs developing mathematical meaning through discourse in multilingual teacher education contexts.- Chapter 7. Expertise of teacher leaders for supporting teachers' implementation of inquiry-based mathematics tasks.- Chapter 8. Developing ways of seeing as mathematics teacher educators.- Part 2. Innovative approaches to MTEs’ learning and expertise development :Chapter 9. Mathematics Teacher Educator identity in the context of change.- Chapter 10. Bodymarking: An Interpretive Process to Support Teacher Noticing.- Chapter 11. Mathematics teaching practices in pre-service teachers: Exploring my identity as a mathematics educator.- Chapter 12. Being a Former Teacher with Supportive Roles for Mathematics Teacher Educator.- Chapter 13. The noticing of a Teacher Educator’s Noticing of Classroom Teachers in the Context of Learning to Teach through Problem Posing.- Chapter 14. A duoethnographic approach to thinking about pre-service mathematics teaching.- Part 3. Distinguished MTEs’ expertise: Experiences, conceptions, learning and development :Chapter 15. From student to teacher to teacher of teachers to teacher of teachers of teachers: Reflections from treading along a long winding road.- Chapter 16. Problems of practice: Fertile ground for mutual learning through research linked development in mathematics teacher education in South Africa.- Chapter 17. Stories of becoming a mathematics teacher educator: Awarenesses arising through experiences to issues to actions.- Chapter 18. Memories and reflections of a teacher educator.- Chapter 19. Mathematics teacher professional development: Low Floor, High Ceiling.- Chapter 20: Mathematics teacher education as a subversive activity: Finding spaces for innovation and agency.- Chapter 21. What lies behind a way of working?.- Chapter 22. Being a teacher educator: three developmental roles.- Chapter 23. Working with preservice mathematics teachers: Raising issues and exploring ways to answer.- Chapter 24. Insights from a mathematics teacher educator working in Brazil.- Chapter 25. On emerging as a phenomenologist: Issues and resolutions.- Chapter 26. M and ME in MDs, then being an MTE in EDs – six universities in three countries: but never an MT for me.- Chapter 27. Reflections of a mathematics teacher education.- Chapter 28. Design and Implementation of Precision Training Based on Intelligent Assessment for Professional Development of Initial Mathematics Teacher.- Chapter 29. The three revelations: 40 years later.-  Chapter 30. From Professional Learning to Preparing Professional Learning Facilitators: Expanding My Horizons.- Chapter 31. Reflections on being a mathematics teacher educator.- Chapter 32. Commentary on mathematics teacher educator's expertise: Experiences, conceptions, Learning and development.