Internet technologies enable the business-to-business (B2B) or the highest level of supply chain management (SCM) maturity, which is the extended supply chain. How pervasive is Internet usage and what impact is it having on extended supply chains? What practices are impacted the most from this new technology? In this chapter, we offer definitions and measures of the extended supply chain and review the results of a benchmarking research project completed in cooperation with the U.S. and European Supply Chain Councils. Our research found that Internet usage is just beginning in both the United States and Europe, but has significant relationships to cross-company (B2B) integrating practices that are key components of the extended supply chain and SCM performance.