This book continues the MRS series on characteristics and properties of cementitious materials. In Part I, recent advances in microstructure and related characterization of cementitious systems are the focus. Topics include: microstructures of “normal” cement systems; microstructure of 'unusual' cement systems; image analysis, modelling and fractal analysis applications; and assessment of pore structures. Part II features presentations on interfacial microstructures, as well as information on elastic and fracture properties, transport properties, and the effects of interfaces on fiber-reinforced systems.