SSA administers two disability programs: the Social Security Disability Insurance (DI) program, enacted in 1956, and the Supplemental Security Income (SSI) program, enacted in 1972. In order to be eligible for DI or SSI benefits based on a disability, an individual must meet the definition of disability for these programs-that is, they must have a medically determinable physical or mental impairment that (1) prevents the individual from engaging in any substantial gainful activity and (2) has lasted or is expected to last at least 1 year or result in death.