Rumball became the secretary of the Rochester City Club when it was formally organized in 1910 to provide programs for weekly luncheons at a downtown hotel. Membership grew to be in the hundreds, and the programs, which included such speakers as Jane Addams and Felix Frankfurter, often made headline news. Women, who had their own Women's City Club, were expected to listen from the balcony. Mary Gannett created a stir by inviting two African American men to sit with her in the balcony who later joined the club as regular members. She was also invited to accompany two speakers to the platform: anarchist Emma Goldman and African American scholar and activist W. E. B. Du Bois. She joined the club herself when membership was opened to women in 1937.