Progressive-era "poverty warriors" cast poverty in America as a problem of unemployment, low wages, labor exploitation, and political disfranchisement. In the 1990s, policy specialists made "dependency" the issue and crafted incentives to get people off welfare. Poverty Knowledge gives the first comprehensive historical account of the thinking behind these very different views of "the poverty problem," in a century-spanning inquiry into the politics, institutions, ideologies, and social science that shaped poverty research and policy.

Alice O'Connor chronicles a...