The aim of the study is, first, to describe the phenomenon of unaccompanied foreign minors in Spain, Italy, France and Germany. Some important elements �such as incidence, origin and relation to criminality � are thoroughly described. As a result, it is possible to begin to understand the psychosocial, legal and penal problems related to the phenomenon in the European context. A second aim is to show the results of a retrospective study. The source of data is a sample of the proceedings registered in the Juvenile Courts of the Basque Country (Spain). The psychosocial profiles of three groups of minors are compared: a) accompanied immigrant minors, b) unaccompanied immigrant minors, and c) non immigrant minors. Our hypothesis is that more significant differences will be found between accompanied and unaccompanied minors, and not between immigrant and non immigrant ones; suggesting that the criminogenic factor is not the migrant experience but the lack of familiar and social references. Some strategic lines for social intervention are suggested, which could have a significant impact on social exclusion reduction and, as a consequence, on crime prevention.