This volume discusses concrete concepts for teacher training and professional development, specifically aimed at supporting mathematics teachers in teaching heterogeneous and particularly inclusive classes. At the methodological level, the focus is on how practical aspects can be integrated into courses and training sessions. The content covers a spectrum of various topics in the context of heterogeneity, such as diagnosis and support, differentiation, giftedness, language, and inclusion. The increasing heterogeneity of students presents a challenge for teachers, which teacher education must prepare for. Special requirements arise in all types of schools due to increased performance heterogeneity and the inclusion of learners with disabilities. Managing a range of performance levels, from learning difficulties to advanced capabilities, is essential.