This book constitutes the thoroughly refereed post-workshop proceedings of the International Workshop on the Unified Modeling Language, <>'98: Beyond the Notation, held in Mulhouse, France in June 1998. The 33 revised full papers presented were carefully selected by the editorial committee after two rounds of reviewing. The volume presents state-of-the-art R&D results as well as advanced applications; it is indispensible reading for anybody seriously interested in UML.