Doing Their Bit
Doing Their Bit may refer to:

Doing Their Bit (1918 film series), a documentary film by Jennie Louise Touissant Welcome and her husband about African American soldiers in World War I
Doing Their Bit (1918 film), a William Fox film by Kenean Buel about a pair of girls who discover spies
Doing Their Bit: Wartime American Animated Short Films, 1939-1945 a book about American animated wartime propaganda films by  Michael S. Shull  and David E. Wilt 
Doin' Their Bit, a 1942 Our Gang comedy film