Born in Brooklyn, New York City, Ruth Joan Bader is the second child of Nathan and Celia Bader, Russian Jewish immigrants, who lived in the Flatbush community. The Bader's older child, Marylin, passed away at age six when Ruth was still young. At age 13, Ruth acted as the "camp rabbi" at a Jewish summertime program at Camp Che-Na-Wah in Minerva, New York.
Celia had actually been an excellent trainee in her youth, finishing from high school at age 15, yet might not enhance her own education since her household picked to send her sibling to college instead of her. Celia desired to see her child get more of an education, which she believed would permit Bader to end up being a high school history instructor. Bader went to James Madison High School, whose law program later on devoted a courtroom in her honor.