Virtually every definition of charter schools asserts that they are a form of public schooling. This article poses the question: In what way ? Charter school advocates, observers, and opponents all note that the schools are publicly funded, are open to all, and are chartered by public entities. This analysis pursues the question by comparing the rhetoric regarding the definition of public education employed by charter school reformers in one state, Michigan, with that of the common school reformers of the 19th century, particularly Horace Mann. The analysis finds conflicting definitions of what constitutes public schooling. Although both reforms support tax-funded schools and open access, the common school reformers emphasized political-democratic forms of control. Charter school advocates actively challenge such control, and elevate market mechanisms of consumer choice and competition between providers as the primary means of authority. To advance such a program, proponents of charter schools explicitly seek to "redefine" popular conceptions of what constitutes public and private education. In doing so, they frame education principally as a consumer good, and, this article theorizes, effect a Privatization of the purpose of public education that contrasts with the common school reformers' stated concern for democracy and the public good.