Given that around 50% of the world's population live in cities, and that urban populations are expanding rapidly, the issues are important and becoming increasingly urgent. To reduce the effects of such impacts, management is required irrespective of whether the groundwater is to be used or not. This management must be based on a sound technical understanding of the interacting processes involved. The forty papers in this volume explore the state of this understanding in the context of a wide range of countries (and therefore cultures), climates, and geologies. They are divided into topic areas covering flow, chemical water quality, biological water quality, remediation, engineering, and socio-economics. An initial section sets the scene with a range of integrated regional-scale studies. The volume provides an insight into groundwater issues for other urban specialists, including planners: without communication between the disciplines involved, progress towards acceptable urban sustainability will be slow.