This chapter focuses on the identification of land use changes in a group of municipalities located in the Douro River Valley in northern Portugal. A combination of satellite and cartographic imagery was used to create a database of digital information that was treated, validated and ultimately used to crete thematic maps according to desired parameters. Land use changes were identified and quantified for selected municipalities for 1990 and 2000. A series of parameters was calculated in order to identify and quantify the processes that originated the land occupation changes. Overall results show that albeit the most significant, urban uses generally occur in a small percentage of the total area under scrutiny. Agricultural uses, particularly those concerning vineyard farming, continue to dominate the landscape, with a tendency to increase in certain municipalities. This is thought to be one of the driving forces behind the loss of forested areas, where woods have been replaced by vineyards. The existence of large non-cultivated areas in the region is possibly caused by the propensity for the occurrence of wild fires, along with the characteristic mountainous topography of the region. The municipalities of Mesão Frio and Sabrosa were selected to illustrate more specific considerations.