Marcel Dijkers PhD studied sociology in the Netherlands and the USA, and through medical sociology entered the field of physical medicine and rehabilitation (PM&R) research. He joined the faculty of the Mount Sinai School of Medicine Department of Rehabilitation Medicine in 1999, and now has the rank of Research Professor. He has researched the social and functional consequences of traumatic brain injury and spinal cord injury, the delivery of health services for individuals with these conditions, as well as the determinants of community integration, quality of life and other outcomes. A systematic review of the descriptions of treatments in PM&R treatment research reports got him interested in the description and classification of treatments and other interventions used with people with disabilities. His first grant proposal for the development of a rehabilitation treatment taxonomy (RTT), which (thankfully) was not funded, dates to 1999. Dr. Dijkers’ research has been supported by grants from the National Institute on Disability and Rehabilitation Research and the Centers for Disease Control, among others. He is a past President of the American Congress of Rehabilitation Medicine, for which he served as the chair of a task force on treatment taxonomy. The work of this task force resulted indirectly in the effort which produced the RTT framework now being proposed. Dr. Dijkers sits on the editorial board of the Journal of Head Trauma Rehabilitation and is a frequent peer reviewer for a number of other journals. He also regularly serves as proposal reviewer for grant-making public and private organizations, in the USA and overseas.