It has long been recognized that groundwater plays a central role in the development of human societies. Groundwater resources are readily and reliably available compared with surface water resources.  In many contexts, the presence of groundwater ensures the presence of life itself. The XXXII IAH (International Association of Hydrogeologists) and VI ALHSUD (Latin-American Association of Groundwater Hydrology for Development) Congress on Groundwater and Human Development, held in 2002, in Mar del Plata (Argentina), brought together over 400 participants from more than 40 countries.  This lively gathering of water enthusiasts exchanged experiences of both fieldwork and research. Topics under discussion and scrutiny included: Groundwater and Quality of Life; Groundwater in Urban, Suburban and Rural Systems; Transboundary Aquifers; Hydrogeology of Large Plains; Coastal Aquifers; Methods for Groundwater Studies; and Education about Groundwater and Groundwater Management. This book contains selected papers, plenary lectures and material from workshops, illustrating the contribution of modern hydrogeology to sustaining humanity's thirst for fresh and safe water.