Always a Sister is the inspiring story of Lillian D. Wald (1867-1940), a pioneer in the early public health movement. In 1893 Wald founded the Visiting Nurse Service and the Henry Street Settlement in New York City. She continued actively to direct the settlement throughout a long career that encompassed activism on many issues.

Wald was instrumental in the shaping of national health care policies, which she insisted must be for everyone, and which she saw as connected to the problems of poverty, urban crowding, militarism, sex inequality, and racism. As president of the American Union Against Militarism (a parent of the American Civil Liberties Union) and founder of the Women's Peace Party, she led a peace delegation that attempted to dissuade President Wilson from entering World War I.

During her lifetime, Wald worked closely with many of the major women activists of the period, including Eleanor Roosevelt, Jane Addams, Crystal Eastman, Florence Kelley, Mary White Ovington, and Angelina Grimke. While exploring Wald's life and work as a champion of health care for everyone, Always a Sister is also indispensable documentation of work of women reformers in the Progressive Era.