Carefully blending theory and practice, this book presents a comprehensive approach to assessing the impact of unplanned events on the cost of engineering complex systems. It illustrates how probability theory is applied to model, measure, and manage risk in the cost of a systems engineering project. The book contains numerous mathematical and professional anecdotes, case studies, results, observations, and interpretations that clarify the challenges in cost risk analysis. It also includes references, equations, and illustrations, provides theoretical and applied exercises, and uses examples and case discussions derived from systems engineering projects to describe key concepts.