We propose and test a theory explaining how and why decision makers engage in attractiveness discrimination in selection decisions. We integrate status generalization with interdependence theories and contextualize attractiveness discrimination within interdependent relationships among decision makers and candidates. Drawing on status generalization theory, we propose that decision makers associate attractiveness with competence in male but not in female candidates. We then draw on interdependence theory to propose that cooperative and competitive interdependence result in opposing patterns of attractiveness discrimination. When decision makers expect to cooperate with the candidate, they perceive attractive male candidates as more capable cooperators and discriminate in their favor. When decision makers expect to compete with the candidate, they perceive attractive male candidates as more capable competitors, and discriminate against them. Four studies, using different samples, selection tasks, manipulations of candidate attractiveness, and manipulations of interdependence, found evidence consistent with the theory.