This article offers four explanations of why outcome-based education (OBE) has proven to be so controversial. First, OBE requires consideration of the central purposes of compulsory public education, on which there is sharp philosophical disagreement, and the outcome-defining process involves input from many groups with many different perspectives, including students, parents, educators, higher education institutions, employers, community leaders, taxpayers, and policymakers. Second, conflict has arisen between two kinds of OBE and between the interest groups allied with one version or the other. The original version of OBE confined itself fairly narrowly to academic achievement, while the other version (known as transformational OBE) encompasses not only academic knowledge and competence but also affective and attitudinal dimensions of learning. Third, OBE is not "just" about outcomes, but involves a relationship between outcomes and inputs, which are often questions of cost. Fourth, OBE has become a contest for control over the "culture" of education, emphasizing not the actual goals proposed for inclusion in OBE but who proposes them. The four explanations are designed to help construct a framework for understanding and engaging in the OBE debate. (JDD)