This text describes the development of augmentative and alternative communication. The focus is not on disabilities, although the atypical developmental paths to language described in this book are caused by a variety of disabilities, but on the developmental achievements of children using augmentative and alternative communication systems. This book is a first attempt to look at the achievements of children using alternative language forms from a broad developmental perspective and discuss how their semantic, grammatical and pragmatic development is promoted through social interactions, both planned and incidental in nature, that take place in particular sociocultural circumstances. The authors use small group data and dialogues to show how the children use grammatical structures and strategies to convey meaning and solve communicative challenges. The overall aim of the book is to inspire a shift towards a developmental understanding of augmentative and alternative communication in both research and clinical practice, leading to new knowledge and a better basis for intervention practices, and thereby to improved social and societal participation for children using augmentative and alternative communication.