The authors provide an excellent guide to the use of UML. They go well beyond the official OMG standards document by providing insight into the history and use of UML constructs as well as an evaluation of its strengths and weaknesses. The book includes many examples that illustrate different concepts, including a sample application (Calendarium) that is threaded through the book. The authors use marginal notes effectively to allow readers to skim chapters and to quickly find topics of interest.