This article presents the results of an investigation carried out across 20+ country-regions under the auspices of ICMI Study 15 into the structures, approaches and general characteristics of the mathematics preparation and development of teachers. We use a global framework provided by the larger research literature on teacher education to contextualize the findings. The article provides an analytic perspective on (a) teacher education systems' characteristics including institutional arrangements and regulations; (b) teacher's recruitment, selection, and credentials; (c) teacher education programs' structure and approaches; (d) teacher educators' characteristics; and (e) the structure and content of the curriculum. This article highlights the important differences and similarities across systems that provide mathematics education and development to teachers. This article concludes with a discussion on implications for future empirical research on mathematics teacher education.