The concepts of object oriented data models aim towards modeling of application objects close to the user's view. Yet developers of applications relying on object oriented database management systems are facing problems resulting from the limitations of object oriented data models to describe adequately the full range of possible associations between objects and between processes. This paper focuses on the conceptual data modeling needs of object oriented database applications, and proposes an object+relationship model, ERC+, which meets database application requirements by merging traditional semantic data models features with object oriented capabilities such as structural object orientation, inheritance, and object identity. It is an extended entity-relationship model specifically designed to support complex object description and to allow multiple perceptions of objects. The ERC+ model provides the foundations for an integrated environment of tools called SUPER that has been designed to aid the development of database applications. The key features of the SUPER environment include: a graphical schema editor for describing complex objects, a data browser and a graphical editor for formulating ERC+ queries.