Five parts of the book give answers to following questions: how to identify most probable critical failures? How to describe and use data concerning material, which are heterogeneous or time-variant or space-variant? How to quantify the reliability or the lifetime of a system? How to use feed back informations to actualize reliability results? How to optimize an inspection politic or a maintenance strategy? A dozen authors from public research centers or firms propose a synthesis of methods, well known and new, providing numerous examples: dams, geotechnical study, structures from nuclear or civil engineering.