Based on the authors’ more than fifteen years of experience in software agent technology, this book first presents the essential basics, aspects, and structures of the agent technology. It then covers the main quality aspects in software system development and gives current examples of agent measurement and evaluation. Focusing on software agent systems and multi-agent systems (MAS), the authors discuss the determination of quality properties. They also explain different techniques and approaches to evaluate the development of MAS. The final chapter summarizes quality assurance approaches for agent-based systems and discusses some open problems and future directions.