Mats-Ake Hugoson, Thanos Magoulas, Kalevi Pessi. EJISE - Volume 14 Issue 1, ECIME 2010 Special Issue / Jan 2011. The strategic role of IT and its significance throughout the organization increases complexity, variety, and the need of change. Hence IT management must deal with uncertainties derived from different, conflicting and ever changing demands. In this sense Enterprise Architecture is playing an increasingly important role in improving IT management practice. If contemporary organizations do not succeed in managing architectural issues, there is a clear risk that considerable resources will be invested without achieving desirable effects. This paper investigates how Enterprise Architecture Principles impact on the management of IT%u2011investments in the context of large organizations. The purpose of the paper is to provide a deeper insight of the relationship between Enterprise Architecture and management of IT Investments throughout the elucidation of two significant types of principles: Delineation (differentiation) principles and Interoperability (integration) principles. Our conclusion is that the choice of architectural principles has an impact both on alignment between information systems and business demands and on the management of IT investments. This impact concerns at least four aspects: (1) The responsibility for IT investments (2) Time to value (3) Long term alignment, (4) Coordination of investments in information systems with changes in business processes.