1. Metasomatism and the chemical transformation of rock: Rock-mineral-fluid interaction in terrestrial and extraterrestrial environments. -2. The Chemical Composition of Metasomatic Fluids in the Crust -- 3. Thermodynamic modeling and thermobarometry of metasomatized rocks -- 4. Structural controls of metasomatism on a regional scale -- 5. Mechanisms of metasomatism and metamorphism on the local mineral scale: The role of dissolution-reprecipitation during mineral re-equilibration. - 6. Geochronology of metasomatic events.-7. Effects of metasomatism on mineral systems and their host rocks: alkali metasomatism, skarns, greisens, tourmalinites, rodingites, black-wall alteration and listevenites -- 8. Metasomatism within the ocean crust -- 9. Metasomatism in subduction zones of subducted oceanic slabs, mantle wedges, and the slab-mantle interface -- 10. Metasomatism during High-Pressure Metamorphism: Eclogites and Blueschist-Facies Rocks -- 11. Prograde, peak and retrograde metamorphic fluids and associated metasomatism in upper amphibolite to granulite facies transition zones -- 12. Mantle Metasomatism -- 13. Mapping the distribution of fluids in the crust and lithospheric mantle utilizing geophysical methods -- 14. A Hydromechanical Model for Lower Crustal Fluid Flow -- 15. Metasomatism in the early solar sysem: The record fron Chondritic meteorites. Fluid-aided mass transfer and subsequent mineral re-equilibration are the two defining features of metasomatism and must be present in order for metamorphism to occur. Coupled with igneous and tectonic processes, metasomatism has played a major role in the formation of the Earth's continental and oceanic crust and lithospheric mantle as well as in their evolution and subsequent stabilization. Metasomatic processes can include ore mineralization, metasomatically induced alteration of oceanic lithosphere, mass transport in and alteration of subducted oceanic crust and overlying mantle wedge, which has subsequent implications regarding mass transport, fluid flow, and volatile storage in the lithospheric mantle overall, as well as both regional and localized crustal metamorphism. Metasomatic alteration of accessory minerals such as zircon or monazite can allow for the dating of metasomatic events as well as give additional information regarding the chemistry of the fluids responsible. Lastly present day movement of fluids in both the lithospheric mantle and deep to mid crust can be observed utilizing geophysical resources such as electrical resistivity and seismic data. Such observations help to further clarify the picture of actual metasomatic processes as inferred from basic petrographic, mineralogical, and geochemical data. The goal of this volume is to bring together a diverse group of geologists, each of whose specialities and long range experience regarding one or more aspects of metasomatism during geologic processes, should allow them to contribute to a series of review chapters, which outline the basis of our current understanding of how metasomatism influences and helps to control both the evolution and stability of the crust and lithospheric mantle.