The safe and continued functioning of critical infrastructures—such as electricity, natural gas, transportation, and water—is a social imperative. Yet the complex connections between these systems renders them increasingly precarious. Furthermore, though we depend so heavily on interconnected infrastructures, we do not fully understand the risks involved in their failure.Emery Roe and Paul R. Schulman argue that designs, policies, and laws often overlook the knowledge and experiences of those who manage these systems on the ground—reliability professionals who have vital insights that would be invaluable to planning. To combat this major blind spot, the athors construct a new theoretical perspective that reveals how to make sense of complex interconnected networks and improve reliability through management, regulation, and political leadership. To illustrate their approach in action, they present a multi-year case study of one of the world's most important "infrastructure crossroads," the San Francisco Bay-Delta. Reliability and Risk advances our understanding of what it takes to ensure the dependability of the intricate—and sometimes hazardous—systems on which we rely every day.