This article analyzes class formation of the Milwaukee Teachers' Education Association (MTEA). In 2011, Wisconsin curtailed public-sector union collective bargaining, causing Wisconsin unions' membership and political power to plummet. This article puts the 2011 collapse into historical perspective, by considering the development of Milwaukee teachers' labor organizing over the course of the twentieth century. In part I, I chronicle the formation of the MTEA, including its early contest with the Milwaukee Teachers Union (MTU) and the gendered fault lines of the teachers' collective vision. In part II, I discuss the consequences of teachers' rhetorical contradictions, especially their lack of collaboration with the civil rights movement in Milwaukee. This article challenges the notion that class movements are preordained with unified interests and aims, and instead shows that unions themselves build and assemble people's political ideas, either to expand solidarity or to narrow it.