Although the mother of four young children, Belle joined her husband in his political campaigns that resulted in him being elected governor of Wisconsin in 1900.
La Follette supported Woodrow Wilson in the 1912 presidential election and approved his social justice legislation. However, she was totally opposed to Wilson's decision to enter the First World War. Once war was declared La Follette campaigned against conscription and the passing of the Espionage Act.
After the war La Follette was an active member of the Women's International League for Peace and Freedom. When Robert La Follette died on 18th June, 1925, Belle turned down invitations to take her husband's Senate seat. Instead her son, Robert LaFollette Jr., replaced him.
Belle La Follette died on 18th August, 1931.