Office of Civilian Defense was a United States federal emergency war agency set up May 20, 1941, by Executive Order 8757 to co-ordinate state and federal measures for protection of civilians in case of war emergency.

Fiorello La Guardia was the first head of the office, succeeded in 1942 by James M. Landis, followed in 1944 by General William N. Haskell.

While the agency only had a paid staff of 75, it supervised and coordinated the efforts of civilian volunteers estimated to have topped 11 million.

[citation needed] Volunteer tasks included firefighting and air-raid preparedness.

Children, under adult supervision, could volunteer in the Junior Citizens Service Corps, and were especially helpful in wartime scrap drives.