The International Classification of Functioning, Disability and Health (ICF) is an internationally used classification that was developed as a complement to the International Classification of Diseases (ICD). It was adopted by the World Health Organization (WHO) in 2001 and defines components of health and some health-related components of well-being. What is special about the ICF is that it describes functioning and disability from biological, individual, and societal perspectives. Since the ICF is legally mandated as a concept for rehabilitation in Germany, the book aims to introduce the thinking and working methods of the ICF, to present the implementation of the ICF in clinical routines, as well as to explore the possibilities and limitations of the ICF for the rehabilitation of children and adults.