The traditional disease and diagnostic medical model is not always useful to brain injury professionals who need to describe, measure, and compare deficits associated with neurologic insult. Professionals in neurorehabilitation are in need of new systems that will assist them in identifying impairments and areas of intervention. The aim of this article is to present the International Classification of Functioning, Disability and Health (ICF), and its applications to brain injury rehabilitation. This taxonomy, developed by the WHO, allows the classification and assessment of functioning and disability in everyday activities and social involvement for individuals with medical conditions. Multi-disciplinary teams from 65 countries have collaborated in the development of the ICF to develop a tool that serves different purposes and disciplines with high trans-cultural validity. It can be of great value for professionals working in the field of brain injury who need to describe and quantify in detail neurocognitive, emotional, and sensory-motor functions as well as their impact on activities and participation in life situations. Its applications also extend to the domains of epidemiology, public health and public policy.