The interaction of the lithosphere and hydrosphere sets the boundary conditions for life, as water and the nutrients extracted from rocks are essential to all known life-forms. Water-rock interaction also affects the fate and transport of pollutants, mediates the long-term cycling of fluids and metals in the earth's crust, impacts the migration and storage of hydrocarbons in sedimentary basins, contributes to the carving and evolution of landscapes, and affects the evolution of geothermal and volcanic activity. At the longest timescales, water-rock interaction draws down carbon dioxide from the atmosphere and impacts climatic evolution. Several tools have contributed over the last decades to our growing understanding of water-rock interaction. For example, new uses of isotopes have led to novel interpretations of the evolution of fluid and rock chemistry over time. New modelling techniques have allowed elucidation of multi-component reactive transport at all temperatures and depths in the crust, while new microscopic and spectroscopic techniques have been used to investigate mineral surfaces and nanophases in environmental systems. New tools from molecular biology are now probing micro-organisms living at depth and at the surface of the Earth. In addition, field investigations measure ongoing water-rock interaction in modern day systems, allowing comparison to such interactions documented in the geological record. The 334 papers published in Volumes 1 and 2 of these Proceedings summarize current research from around the world on the broad area of water-rock interactions. These research results are of broad interest to students and professionals in geochemistry, hydrology, geology, environmental microbiology, vulcanology, and water chemistry studying both the fundamental and applied aspects of energy and natural resources.