To determine the relative incidence, prevalence, costs, and impact on disability of 8 common conditions treated by rehabilitation professionals. Comprehensive bibliographic searches using MEDLINE, Google Scholar, and UpToDate, (June, 2013). Two review authors independently screened the search results and performed data extraction. Eighty-two articles were identified that had relevant data on the following conditions: Stroke, Spinal Cord Injury, Traumatic Brain Injury, Multiple Sclerosis, Osteoarthritis, Rheumatoid Arthritis, Limb Loss, and Back Pain. Back pain and arthritis (osteoarthritis, rheumatoid arthritis) are the most common and costly conditions we analyzed, affecting more than 100 million individuals and costing greater than $200 billion per year. Traumatic brain injury, while less common than arthritis and back pain, carries enormous per capita direct and indirect costs, mostly because of the young age of those involved and the severe disability that it may cause. Finally, stroke, which is often listed as the most common cause of disability, is likely second to both arthritis and back pain in its impact on functional limitations. Of the common rehabilitation diagnoses we studied, musculoskeletal conditions such as back pain and arthritis likely have the most impact on the health care system because of their high prevalence and impact on disability.