A key issue for strategic supply chain management research is whether purchasing can be a source of long-term competitive advantage. Recent resource-based works in strategic management suggest that purchasing cannot be a source of long-term competitive advantage. In contrast, recent works in supply chain management suggest that purchasing can be such a source. This article explains why works in strategic management and supply chain management come to such radically different conclusions on purchasing strategy. Specifically, this article points out that the negative conclusion concerning purchasing strategy is derived from theories of competition based on the neoclassical, equilibrium economics research tradition. Therefore, the positive case for strategic purchasing needs to be grounded in a research tradition that provides a clean break from the neoclassical, equilibrium economics research tradition. The authors discuss the characteristics of what has come to be labeled “the resource-advantage research tradition” and offer it as an appropriate grounding for purchasing strategy, in particular, and supply chain management, in general.