The Teacher Education Study in Mathematics (TEDS-M) 2008 is the first cross-national study to provide data on the knowledge that future primary and lower-secondary school teachers acquire during their mathematics teacher education. It is also the first major study to examine variations in the nature and influence of teacher education programs within and across countries. The impetus for TEDS-M, conducted in 17 countries under the aegis of the International Association for the Evaluation of Educational Achievement (IEA), was recognition that teaching mathematics in primary and secondary schools has become more challenging worldwide as knowledge demands change and large numbers of teachers reach retirement age. It has also become increasingly clear that effectively responding to demands for teacher preparation reform will remain difficult while there is lack of consensus on what such reform should encompass and while the range of alternatives continues to be poorly understood let alone based on evidence of what works. TEDS-M accordingly focused on collecting, from the varied national and cultural settings represented by the participating countries, empirical data that could inform policy and practice related to recruiting and preparing a new generation of teachers capable of teaching increasingly demanding mathematics curricula. Two particular purposes underpinned this work. The first was to identify how the countries participating in TEDS-M prepare teachers to teach mathematics in primary and lower-secondary schools. The second was to study variation in the nature and impact of teacher education programs on mathematics teaching and learning within and across the participating countries. The key research questions for the study focused on the relationships between teacher education policies, institutional practices, and future-teachers' mathematics content knowledge and mathematics pedagogy knowledge. The 17 countries that participated in TEDS-M were Botswana, Canada (four provinces), Chile, Chinese Taipei, Georgia, Germany, Malaysia, Norway, Oman (lower-secondary teacher education only), the Philippines, Poland, the Russian Federation, Singapore, Spain (primary teacher education only), Switzerland (German-speaking cantons), Thailand, and the United States of America (public institutions only). Appended are: (1) Supplementary Exhibits Relating to Chapters 3, 4, 6, and 7; (2) Sampling, Scaling, and Reporting Procedures; and (3) Organizations and Individuals Responsible for TEDS-M. Individual sections contain exhibits, footnotes and references. [This paper was written with the assistance of Jean Dumais, Ralph Carstens, Falk Brese, Sabine Meinck, Inese Berzina-Pitcher, Yang Lu, and Richard Holdgreve-Resendez.]