This reference model for IT management responsibilities covers the most important aspects when modeling, analyzing and evaluating enterprise architecture, EA. The reference model can be employed to support IT management in their quest to make well-informed decisions, e.g. to derive architectural principles in order to obtain a proper scope for EA activities, measure the status of the current EA, follow up changes committed, and evaluate alternative EA scenarios. The model is based on extensive literature studies and has been tested in a series of empirical studies.