The WHO Disability Assessment Schedule (WHODAS 2.0) is a unique practical instrument, based on the International Classification of Functioning, Disability and Health (ICF), that can be used to measure general health and disability levels, including mental and neurological disorders, both at the population level or in clinical practice, in a wide range of cultural settings. Presented in this book is a detailed overview of how the schedule was developed and validated, together with a description of its key features and applications. The questionnaires that form the basis of WHODAS 2.0 are available in three versions (36 item, 12 item, and 12 + 24 item), which are reproduced in the book, accompanied by detailed practical guidelines on how to use them effectively.The publication is aimed at all health professionals who are involved in studying disability and health. It will be of interest to general health workers, psychiatrists, psychologists, neurologists and specialists in addiction problems.