The Office of Local Defense Community Cooperation (OLDCC), formerly the Office of Economic Adjustment (OEA), is a United States Department of Defense (DoD) field activity and provides technical and financial assistance to states, territories, and communities that are invested in the defense mission. OLDCC assistance supports the readiness and resiliency of both defense installations and defense communities.

To assist affected communities, OLDCC manages and directs the Defense Economic Adjustment Program and coordinates the involvement of other federal agencies.

Founded in 1961 under President John F. Kennedy and Defense Secretary Robert McNamara, the Office of Economic Adjustment (OEA), later the Office of Local Defense Community Cooperation (OLDCC), was tasked with mitigating the adverse impact on jobs and local economies after a government cost-reduction program closed several military bases. In the late-1960s and early-70s, OEA opened regional offices in major cities nationwide to facilitate federal grant deliveries.

In the 1980s, OEA phased out categorical grants (grants with specific categories upon which they can be spent) in favor of block grants (grants with few or no conditions on spending). Regional assistance waned and all offices not on the West Coast were shuttered. No major military bases were closed during the 1980s. In 1988, a new base closure statute was enacted, which was designed to shield the process from political manipulation (Pork barrel politics, i.e. congresspeople ensuring bases in their states or districts remain open for political gain). The law set up a bipartisan commission that channeled base recommendations to the president; approximately 100 bases were closed and 50 realigned.

As a result of the Base Realignment and Closure (BRAC) process developed in the late-1980s and 1990s, OEA provided support to many local communities amidst defense industry cutbacks. OEA's success served as a model for communities within former Soviet States and new Eastern European countries to better cope with reductions in military spending brought about by the end of the Cold War and the dissolution of the Soviet Union.

In 2013, military operations partially subsided as a result of budget sequestration (spending cuts) imposed by the Budget Control Act of 2011, harming Defense Department-dependent states and communities. Seeking to avert similar economic slowdowns, OEA Director O'Brien began issuing the “Defense Spending by State” report to help state and local leaders cope with potential loss of Defense contracts through economic diversification or technological innovation and Defense Secretary Leon Panetta pledged continuing aid to affected communities.

The William M. (Mac) Thornberry National Defense Authorization Act for Fiscal Year 2021 (NDAA FY2021) included a provision (Section 905) that amended Chapter 4 of Title 10 of the United States Code to rename OEA the Office of Local Defense Community Cooperation (OLDCC). The provision took effect upon enactment of the Act on January 1, 2021.

Executive Order 14008, issued by President Joe Biden in early 2021, added addressing climate change to OLDCC's goals.