The United States Social Security Administration (SSA) is an independent agency of the U.S. federal government that administers Social Security, a social insurance program consisting of retirement, disability and survivor benefits. To qualify for most of these benefits, most workers pay Social Security taxes on their earnings; the claimant's benefits are based on the wage earner's contributions. Otherwise benefits such as Supplemental Security Income (SSI) are given based on need.

The Social Security Administration was established by the Social Security Act of 1935 and is codified in 42 U.S.C. § 901 (49 Stat. 635). It was created in 1935 as the "Social Security Board", then assumed its present name in 1946. Its current leader is Kilolo Kijakazi, who serves on an acting basis.

SSA offers its services to the public through 1,200 field offices, a website, and a national toll-free number. Field offices, which served 43 million individuals in 2019, were reopened on April 7, 2022 after being closed for two years due to the COVID-19 pandemic.

SSA is headquartered in Woodlawn, Maryland, just to the west of Baltimore, at what is known as Central Office. In addition to its 1,200 field offices, the agency includes 10 regional offices, 8 processing centers, and 37 Teleservice Centers. As of 2018, about 60,000 people were employed by SSA. Headquarters non-supervisory employees of SSA are represented by American Federation of Government Employees Local 1923.

SSA operates the largest government program in the United States. In fiscal year (FY) 2022, the agency expects to pay out $1.2 trillion in Social Security benefits to 66 million individuals. In addition, SSA expects to pay $61 billion in SSI benefits to 7.5 million low-income individuals in FY 2022.