Granites (sensu lato) represent the dominant rock-type forming the upper–middle continental crust but their origin remains a matter of long-standing controversy. The granites may result from fractionation of mantle-derived basaltic magmas, or partial melting of different crustal protoliths at contrasting P–T conditions, either water-fluxed or fluid-absent. Consequently, many different mechanisms have been proposed to explain the compositional variability of granites ranging from whole igneous suites down to mineral scale. This book presents an overview of the state of the art, and envisages future avenues towards a better understanding of granite petrogenesis. Particular emphasis of this Volume is on the following topics: Compositional variability of granitic rocks generated in contrasting geodynamic settings during Proterozoic to Phanerozoic Periods, Main permissible mechanisms producing subduction-related granites, Crustal anatexis of different protoliths, and the role of water in granite petrogenesis, New theoretical and analytical tools available for modelling whole-rock geochemistry, in order to decipher the sources and evolution of granitic suites.