This article examines an important class of information system that serves as the foundation for corporate energy and greenhouse gas (GHG) accounting: energy and carbon management systems (ECMS). Investors, regulators, customers, and employees increasingly demand that organizations provide information about their organizational energy use and GHG emissions. However, there is little transparency about how organizations use ECMS to meet such demands. To shed light on ECMS implementation and application, we collected extensive qualitative interview data from two service-sector organizations: one that uses a spreadsheet-based ECMS and another that implemented an ECMS provided by a third-party vendor. Our analysis of collected data revealed numerous challenges in the areas of business processes, managerial capabilities, data capture and integration, and data quality. Though our study is built on only two organizations and requires confirmation in large-sample surveys, we provide several recommendations for organizations regarding ECMS. We also provide suggestions for future studies to build on our tentative results.