UML A Beginner's Guide

Jason T. Roff
2003

Knowing nothing about UML, other than a rough idea of what it is, I found this a very useful reference book and am ordering a copy for school from Fishpond.
Each module follows a similar format, addressing the topics of

• defining the type of diagram described
• explaining why the type of diagram is used
• identifying the components of the diagram type
• demonstrating how to make the diagram

Each module then offers a project that follows the "how to" steps, and then shows a model answer.
The book is supported by online diagram files (click the Code link on this page to download a zipped folder of the project diagram files).