Augmented and virtual reality (AR/VR) are technologies of increasing importance in our society. In the field of mathematics education, these innovative technologies may offer a wide range of opportunities to support immersive, individual, and active learning processes. At the same time, many new challenges arise that need to be mastered by teachers and students in the classroom. With this book we want to contribute to the discourse by presenting innovative insights by bringing parties from research and practice together. The papers cover a wide range of relevant topics including cooperation and communication, STEM and modelling, development and application of design criteria, spatial geometry and imagination or teacher-trainings. The contributions include in-depth theoretical considerations, concrete developed applications and learning environments, and findings from empirical studies.