The design of structural components with nominally brittle materials is largely determined by their elastic moduli, density, and tensile strength. This article discusses some of the factors involved in the design and reliability through considerations of toughness and ductility of nominally brittle materials. It describes toughening by various bridging mechanisms, as well as process zone effects and their interaction with the bridging rupture zone. The article explains the phenomena that give rise to exceptional toughness and notch-insensitive mechanical behavior. It provides a schematic illustration of a basic cell model to characterize the inelastic strains that occur in ceramic-matrix composites...