HUD's mission is to ensure Americans have access to safe, decent, and affordable housing. It enforces the federal Fair Housing Act, which prohibits discrimination in housing based on race, religion, national origin, sex, disability, and familial status, and investigates thousands of housing discrimination complaints each year.

The department's Federal Housing Administration insures mortgages issued by private lenders, allowing millions of homebuyers, particularly first-time buyers and those with smaller down payments, to qualify for financing they might not otherwise access, and has backed more than 47 million home mortgages since its creation in 1934.

HUD also funds public housing authorities and the Housing Choice Voucher program (commonly known as Section 8), which subsidizes rent for millions of low-income households, and distributes Community Development Block Grants that cities and towns use for infrastructure, affordable housing, and neighborhood revitalization projects.

HUD is one of the smallest Cabinet departments in staff but moves a large budget almost entirely as payments to others: about 85 percent of its money goes to rental assistance, and most of the rest to block grants for cities and states and to homeless programs. Its rental programs reach only about one in four eligible low-income households, because Congress funds them at a fixed level each year rather than as an entitlement, so most of the effort goes to managing waiting lists.