Clay minerals are one of the most important groups of minerals that destroy permeability in sandstones. However, they also react with drilling and completion fluids and induce fines migration during hydrocarbon production. In this volume, clay minerals in sandstones are reviewed in terms of their mineralogy and general occurrence, their stable and radiogenic isotope geochemistry, XRD quantification, their effects on the petrophysical properties of sandstones and their relationships to sequence stratigraphy and palaeoclimate. A number of case studies are included for kaolin, illite and chlorite cements, and the occurrence of smectite in sandstone is reviewed. Experimental rate data for clay cements in sandstones are reviewed and there are two model-based case studies that address the rates of growth of kaolinite and illite.