Europe has a long continental and island coastline along which many human activities are concentrated. Coastal aquifer development is often intensive and subject to salinity problems as a result of seawater intrusion, upconing of deep saline water, and residual salinity in aquitards. These coastal aquifers are important freshwater sources that risk being salinized by different processes. Often important coastal aquifers are of relatively small size but crucial to supply human needs, which vary from mostly urban and industrial supply in mid to high latitudes, to dominantly seasonal for irrigation and tourism in the Mediterranean area and many of the islands. To prevent quality loss through salinization, management is needed. This is a complex objective, full of difficulties and with scarce experience. Solutions are highly dependent on local circumstances. Some aquifers are carefully studied, monitored and managed. Examples can be found in different countries, such as The Netherlands, Belgium, and northeastern Spain.