Workplace injuries and illnesses are an important cause of disability. State workers’ compensation programs provide almost $60 billion per year in cash and medical-care benefits for those injuries and illnesses. Social Security Disability Insurance (DI) is the largest disability insurance program in the United States, with annual cash payments to disabled workers of $95 billion in 2008. Because injured workers may also receive DI benefits, it is important to understand how those two systems interact to provide benefits. This article uses matched state workers’ compensation and Social Security data to study the relationship between workplace injuries and illnesses and DI benefit receipt. We find that having a lost-time injury substantially increases the probability of DI receipt, and, for people who become DI beneficiaries, those with injuries receive DI benefits at younger ages. This relationship remains robust even after we account for important personal and work characteristics.