State and federal law mandates that DAHP be the central repository of cultural resource data. The agency manages 10 databases, such as the State Archaeological Site and Historic Property Inventory databases, and 3 official registers of historic places: National Register of Historic Places, Washington Heritage Register, and the Washington Heritage Barn Register. These inventories and registers are used by: federal and state agencies and Tribes for compliance with federal and state cultural resource management laws and regulations. Tribes and government agencies at all levels use this data for compliance with the State Environmental Policy Act and Section 106. Planning and environmental consulting firms use the information for project development as well as property owners, developers, and the general public. The Department of Natural Resources uses the Archaeological Site database as part of the Forest and Fish requirement to ensure that archaeological sites are not impacted by forest practices.

Under state and federal law, the agency reviews all proposals that receive state or federal funding assistance or require a federal license or permit. These project reviews by the agency are performed to assess potential impacts on archaeological sites, human remains, and historic buildings and structures. In cases where project sponsors must apply to DAHP for an archaeological permit, or fulfill mitigation measures as required by a memorandum of agreement (MOA), the agency reviews the applications, establishes appropriate archaeological methodologies, and identifies required conditions that must be met during construction. The agency coordinates closely with affected Tribes, and as applicable, issues a state permit or signs an MOA. When archaeological sites or burials have been disturbed, the agency conducts investigations and takes enforcement action. In cases where federally funded, licensed or permitted undertakings result in the demolition or alteration of a historic building, structure or district, the agency is consulted to identify appropriate mitigation tasks. Adverse effects to historic and archaeological resources result in a negotiated MOA with the federal agency, tribes and other interested parties. The agency also works with Tribes on balancing cultural resource protection with project construction. Finally, the agency proactively works to minimize review times so that project sponsors receive responses in a timely and efficient manner.

Under the National Historic Preservation Act of 1966 and complimentary authority under state law, the agency provides technical assistance to 50 local governments certified by the National Park Service as eligible to receive federal assistance. The agency also conducts the technical review and approval of applications for federal tax incentives related to the rehabilitation of historic properties. In addition, the Department of Archaeology and Historic Preservation develops a statewide historic preservation plan every five years and reviews historic preservation and shoreline management plans developed under the Growth Management and Shoreline Management Acts. The agency also administers the Main Street© program in Washington. This economic development initiative focuses on small business growth and retention in downtowns through the B&O tax credit program, business training and maintenance of the physical environment.