Hull-House was a unique social experiment by which Jane Addams realized her egalitarian vision for a shared civic life. Facing soaring social problems of the early twentieth century, Hull-House's most important mission was to help new immigrants learn the rule of self-government and become successful drivers of it. Hull-House was an unusual group of changemakers, in that many, being women, didn't have the right to vote until the ratification of the Nineteenth Amendment in 1920. Many people coming from different origins with divergent interests, talents, and social backgrounds joined Hull-House's innovative changemaking effort towards communal problem-solving. They learned from one another and collaborated on equal footing with respect for diversity. To address a range of social problems, Hull-House invented what I call "pluralistic civic inquiry," described in four categories in this essay: social inquiry, activist inquiry, cultural inquiry, and educational inquiry. According to Addams, "Americanism"--i.e., the idea of unity--is represented by this entire gamut of pluralistic civic inquiry, not conformity to a particular set of creeds. I conclude with implications of Hull-House's theory and practice for civic education reform today.