‘How to source globally’ has become a critical strategic decision for companies competing on a global basis. Despite an increased focus on global sourcing and supply chain management, little is known about the challenges and solutions surrounding such sourcing practices. Extant literature points at the critical importance of developing and sharing knowledge in multinational companies (MNCs). However, little work has been undertaken to examine the organizational mechanisms used by MNC headquarters for knowledge leveraging across subsidiaries, especially in the area of purchasing and supply management. Based on an in-depth case study, focusing on a chemical company, the actual buying systems for managing the global supply base are explored. Kraljic's purchasing portfolio approach appears useful, both for developing effective purchasing strategies as well as for managing a global supply base.