In 1974, the Office of Policy Planning (OPP) was established within the Executive Department with the purpose of centralizing and systematizing the planning of Seattle's physical and social development. This organization was formed from the Office of Executive Policy (OEP), to which was transferred policy functions from a number of offices and departments, including Grants Management from the Office of Management and Budget (OMB), the Planning and Programming and Economic Development Programs from DCD, and all Comprehensive Policy Plan development efforts heretofore undertaken by individual City departments. OPP was designed with two principal divisions, Policy Management and Policy Development. The Law and Justice Planning division was added in 1975, and tasked with crime analysis and preventative planning. In 1975 the OEP's Intergovernmental Affairs Office was also incorporated into the OPP's Intergovernmental Relations Division.

In 1979, the Office of Policy Planning was converted into the Office of Policy and Evaluation (OPE), once again under the purview of the Executive Department. The new office's mandate was to oversee City planning, evaluation, and policy development activities. The main structural alterations were the removal of the Law and Justice Planning and Intergovernmental Affairs divisions and their subsequent elevation to Office-level positions within the same department. In addition, significant responsibilities and staff assets related to planning were transferred to DCD, including economic data analysis, housing, and citizen participation. The OPE was organized into three divisions: Policy Coordination and Management, Growth Management (changed to Special Policy Development Projects in 1980), and Urban Development and Issues (changed to Policy Analysis and Evaluation in 1980).

In 1982, the Land Use and Transportation Project (LUTP) was formed from those assets of the OPE relating to planning and policy development for land use, transit and transportation, housing, and related economic development. Other OPE functions and personnel, chiefly in the form of the Policy Coordination and Management division, became part of OMB. Among the LUTP's duties was the generation of the Comprehensive Land Use Policies Plan, a comprehensive set of policy guidelines begun in 1978 and finally completed in 1986.

In 1986 the Land Use and Transportation Project was consolidated into a new organization, the Office for Long-Range Planning (OLP). This new entity would be part of a general Planning Program within the Executive Department, along with the newly-formed Office of Strategic Human Services Planning (OSHSP), which would be responsible for human services needs assessment and related policy planning. In addition to LUTP's existing functions, the OLP was tasked with coordinating City policy for physical development, the environment and transportation; establishing a centralized planning database, and conducting long-range planning on issues deemed high-priority by the Mayor and the City Council. By 1989, the OLP was also assigned the job of administering effective City participation in regional planning initiatives, on topics like hazardous waste disposal and public transit. In 1992 the Office of Long-Range Planning and OSHSP were combined to create the new Planning Department.