This practical book is an accessible and authoritative guide to dealing with challenging behavior in children and adults with intellectual or developmental disabilities (IDD), including autism. It recognizes that challenging behavior does not appear out of nowhere and makes sense to the person exhibiting it. Behavior can be communicative and a significant indicator of underlying sensory or environmental issues. Focusing on a person-centered approach, the book provides advice and strategies for working with clients' families, support staff, and professionals. It also presents best practices for analyzing and addressing challenging behavior in various settings such as schools, hospitals, and homes, while emphasizing the need to keep the human story at the heart of every assessment and intervention. Each chapter includes questions for discussion or reflection and exercises for the reader. Informal, honest, and free of technical jargon, this book is essential for professionals, parents, and anyone working with individuals with intellectual disabilities or autism.