A major requirement in Software Engineering is to reduce the time to market. This requirement along with a demand for product sophistication and better quality has led to larger teams which in turn dramatically increases the pressure for more concurrent work in a distributed context. This paper, based on our experience in Software Configuration Management for large software systems, shows why object management in such a context requires specific facilities for the consistent management of objects in multiple copies, different locations and formats, accessed and changed simultaneously by many engineers. We present the solutions we have developed with our partner Dassault Systèmes, for the definition and enforcement of consistent concurrent engineering work, including a number of measures showing that scalability and efficiency are really tough issues. We argue that the scalability and efficiency constraints found in SCM can only be met by a new architecture of SCM systems and by the de...