This book constitutes the refereed proceedings of the 18th International Conference on Conceptual Modeling, ER '99, held in Paris, France, in November 1999. The 33 revised full papers presented together with three invited contributions were carefully reviewed and selected from a total of 143 submissions. The book is divided into topical sections on supporting schema evolution, temporal database design, schema transformation, views and conceptual modeling, reuse in conceptual modeling, business process modeling and workflows, integrating application models, data warehouse design, modeling concepts, schema integration, and advanced conceptual modeling.