A key reason for the popularity of integrated supply-chain management (SCM) is that Web technologies have made supply-chain coordination a viable managerial and strategic option. Building on research in the areas of management information science, supply chains, and organizational innovation, this study explores the use of Web technologies for organizational SCM. Based on an extensive survey of North American organizations, it investigates the assimilation of Web technology systems into internal supply chain functions and their external diffusion into interorganizational supply-chain networks, and also explores the relevant environmental determinants. The findings suggest that internal assimilation and external diffusion of Web technologies both significantly affect the benefits realized by SCM. Supplier interdependence and information technology (IT) intensity are important environmental factors affecting external diffusion. Organizational factors, such as centralization and formalization of the IT unit structure and high levels of managerial IT knowledge, are significant drivers of Web technology assimilation in the SCM function.