This book attempts to answers the following broad What do fibers do to concrete when added to it? What do fibers do to structural concrete when used in combination with reinforcing bars or prestressing strands? It provides extensive information on the behavior and properties of the resulting FRC composite (tension, compression, bending, shear, toughness, fracture energy, ductility, time-dependent properties, fatigue, fire resistance, etc) and on modeling its response (tension, compression, bending, shear) including its elastic modulus as well as the bond at the fiber-matrix interface. Mix design and numerous examples of applications are covered. Effort is made throughout to synthesize and condense essential information and suggest directions in which progress is likely to proceed. The material is presented in 15 chapters with 765 pages, close to 450 figures and photographs and an extensive list of references. The book is written for advanced students, engineers, researchers, educators, and practicing professionals. It is intended as a basic reference, a comprehensive source of information, and a thorough teaching text.