This paper presents an approach and a tool to increase specification quality by using a combination of UML and formal languages. Our approach is based on the expression of the UML class diagram and its annotations into a Z formal specification. Our tool called RoZ supports this approach by making the transition between the UML world and the Z world : from an annotated class diagram, it automatically generates a complete Z specification, the specifications of some elementary operations and some proof obligations to validate the model constraints. S. Dupuy, Y. Ledru, and M. Chabre-Peccoud. An Overview of RoZ : a Tool for Integrating UML and Z Specifications. In 12th Conference on Advanced information Systems Engineering-CAiSE’2000, volume 1789 of Lecture Notes in Computer Science, SpringerVerlag, Stockholm, 2000. The original publication is available at http://www.springerlink.com. LNCS proceedings are available at : http://www.springer.de/comp/lncs/index.html This material is presente...