Model management is a technology evolving by necessity, pushed by the attempts to deal with increasingly complex systems and the perceived inadequacies of past efforts. This rapid evolution of Model Management Systems (MMS) has created different perspectives of the role of the MMS; one arising the user's interaction with a model data bank and the other view from the in the database and decision support systems research community stressing modeling community emphasizing the model development functions. These two perspectives are clarified and reconciled by relating each to the model life cycle, which leads to a more comprehensive statement of MMS requirements.