In this book from the Division on Autism and Developmental Disabilities (DADD), the authors provide educators with research-based interventions and instructional approaches to supporting students with autism spectrum disorders (ASD) and intellectual and developmental disability (IDD) in mathematics. Chapters provide educators with accessible resources that provide research-supported practical strategies and guides to educate students. Each chapter, written by a scholar whose work focuses on mathematics education for students with ASD/IDD, provides examples and materials teachers can use with elementary and secondary students with ASD/IDD.