This book presents a systematic description of the electronic and physico-chemical properties of transition-metal carbides and nitrides. These materials possess remarkable physical and chemical properties, including extremely high hardness and strength, and high melting points, metallic conductivity and superconductivity. As a result, they have been extensively studied by scientists, and their properties widely exploited by engineers. This is the first book devoted to the theoretical modelling of refractory carbides and nitrides and alloys based on them. It makes use of computational methods to calculate their spectroscopic, electric, magnetic, superconducting, thermodynamical and mechanical properties. Calculated results on the electronic band structure of ideal binary transition-metal carbides and nitrides are presented, and the influences of crystal lattice defects, vacancies and impurities are studied in detail. Data available on chemical bonding and the properties of multi-component carbide- and nitride-based alloys, as well as their surface electronic structure are described, and compared with those of bulk crystals. This book will be of interest to solid state physicists, materials scientists and engineers in both university and industrial environments working on or with refractory carbides and nitrides.