Existing research has shown that both IT and data within an organization need to be governed appropriately in order to achieve business value from IT and to ensure data quality, compli-ance, and privacy. For achieving a high level of maturity in IT and Data Governance functions, a combination of governance structures, processes, and mechanisms as well as their establish-ment within the organization is seen as vital. However, organizations today usually act within bigger networks of organizations to achieve value gains usually consisting of a set of heteroge-neous stakeholders pursuing their own goals and having their own IT infrastructures. Especially the way data is exchanged through IT and the quality of this data is of high relevance for inter-organizational business processes. Based on a comparative case study approach, we analyze the challenges of governing IT and data within buyer-supplier relationships drawing upon find-ings from both IT governance and transaction cost economics. The identified challenges are then used to derive implications for an organization’s governance framework based on a ma-turity model. This can help organizations to assess their maturity in terms of value chain gov-ernance concerning both IT infrastructures and data exchange processes.