A comprehensive, up-to-date introduction to the foundations of classical safety engineering, with an emphasis on preparing for future challenges. Systems today are orders of magnitude more complex than in the past, and their complexity is increasing exponentially. Preventing accidents and losses in such systems requires a holistic perspective that can accommodate unprecedented types of technology and design. This textbook teaches the foundations of classical safety engineering while incorporating the principles of systems thinking and systems theory. Beginning with the framing and lessons of her classic text, Safeware, Nancy Leveson builds on established knowledge and brings the field up to date, challenging old approaches and introducing new ones. This essential book provides the core.