The Ebro Basin is located in the northeast of Spain. Its central part is filled with gypsum and carbonate deposits of Neogene age. Quaternary sediments overlie the Tertiary layers. Alluvial sinkholes have developed in this region, causing high economic losses. From the study of aerial photographs, from the compilation of historical cases of collapse and from data on the lithological characteristics of the Quaternary and Tertiary deposits (their structure, morphology, hydrological characteristics, etc.), natural and human factors in sinkhole development have been evaluated. Among the natural variables that may be considered are the lithology of the Tertiary deposits, the thickness and geomechanical behaviour of the Quaternary cover, the morphology of the contact between the Tertiary and Quaternary deposits, fracturing, content of sulphates in groundwater and the depth and seasonal variations of the groundwater level. The irrigation techniques of farmers and the presence of irrigation canals increase the level of the groundwater. Pumping activities may also be important locally.