This book offers results from the comparative “Teacher Education and Development Study – Learning to Teach Mathematics (TEDS-M)". Carried out under the auspices of the International Association for the Evaluation of Educational Achievement (IEA), more than 23,000 mathematics teachers at the primary and lower secondary levels from 16 countries were tested at the end of the teacher education on their mathematics and mathematics pedagogical content knowledge as well as surveyed on their beliefs and their opportunities to learn. In addition, representative samples of teacher educators and training institutions were surveyed. TEDS-M analyses in particular the relationship between teacher education policies, practices and outcomes.  ​