The field of study known as multi-agent systems has been in existence for more than 25 years. During this period it has already been recognized, and supported by both theoretical and practical evidence, that such systems have the potential to improve the practice in software engineering, and even to extend the range of applications that can feasibly be tackled. However, one important aspect of multi-agent systems that still lacks complete and proper definition, general acceptance and practical application, is that of modeling, despite the substantial efforts of an active research community. The focus of this book is thus on an approach to resolving this insufficiency by providing a comprehensive modeling language designed as an extension to UML 2.0, focused specifically on the modeling of multi-agent systems and applications. This language is AML—the Agent Modeling Language—the design of which is informed by previous work in this area while explicitly addressing known limitations relating to managing complexity and improving coverage and comprehension. The book is addressed to researchers, students, software engineers, methodologists, and tool developers with the objective to explain foundation, design principles, specification, and usage of AML.