An Office of Human Resources was established in 1971 in the Executive Department to develop, implement, and manage social services for low-income and disadvantaged residents of Seattle. In 1973 it was replaced by the Department of Human Resources. DHR administered family and youth services programs, senior citizen services, community service activities, the Seattle Veterans Action Center, and the Comprehensive Residential Weatherization Program. Federal, state, and local grants comprised two-thirds of the department's operating budget. Passage of the 1986 Low Income Housing Levy increased the City's funding and policy role in housing issues. In 1991, the agency name was changed to the Department of Human Services. A year later, the Department of Housing and Human Services was created, incorporating the City housing programs and Community Development Block Grant administration from the recently abolished Department of Community Development. DHHS programs included aging services, family and youth services, housing and community services, human services, and the City's education office. In 1999, the Office of Housing was established as an independent agency and DHHS was reorganized as the Human Services Department.

Created in May 1971 as part of the Office of Human Resources in the Executive Department, the Division on Aging has developed and maintained a comprehensive and coordinated planning and service delivery system for older citizens of Seattle and King County. It is sponsored by the City of Seattle, King County and United Way of King County and administers the Mayor’s Office For Senior Citizens. In 1998 its name changed to the Division of Aging and Disability Services.