Intensive use of groundwater has resolved the demand for drinking water and, through irrigation, has contributed to the eradication of malnourishment in many developing countries. The spectacular worldwide increase in groundwater use in the last decades, especially in arid and semi-arid regions, has been a silent revolution carried out by millions of small farmers. In some instances, groundwater abstraction has caused problems of quality degradation, excessive drawdown of groundwater levels, land subsidence, reduction of spring and baseflows or degradation of groundwater-dependent ecosystems. Most of these problems could be anticipated, mitigated, or even avoided with more active water agencies, adequate regulations and users' participation in management. Groundwater Intensive Use contains a selection of papers presented at a symposium held in December 2002 in Valencia, Spain. It constitutes a step forward in creating a greater worldwide awareness of the relevance of groundwater in