In recent years, the American political parties have shifted their positions on elementary and secondary education policy, both relative to each other and to their own past positions. Established explanations for party issue position-taking privilege the influence of groups in the parties' coalitions; yet in this case, both parties have taken positions opposed by important components of their bases. We develop a general framework for understanding party issue position adoption and change that highlights the role of issue definition—the considerations, values, and goals associated with a policy debate at any one time. This framework helps us to explain the participation and preferences of groups regarding an issue; the perceived ideological fit and strategic benefits of issue positions for parties; and how parties negotiate and manage issue conflict within their coalition. We apply that framework to the case of education policy, showing how education issue definition has changed over time—from a focus on resources and equality to an emphasis on values and excellence—and how those changes have been consequential for each party's changing, and converging, positions on education policy. We conclude by discussing the potential application of our model of party issue positioning to other issues in American politics.