Compared to other countries in Western Europe, Sweden has a rather high percentage of immigrants; 5.7 percent of the population has a foreign nationality. Apart from immigrants, Sweden is host to many refugees and persons seeking asylum, and the number of persons seeking asylum has gradually increased since the beginning of the 1980's. Sweden is attractive to immigrants because it is one of the most advanced welfare states in the world. Swedish criminal statistics show that foreign nationals are clearly overrepresented among persons suspected of crime; the percentage of foreign citizens suspected of criminal acts increased from 15 to 22 percent during the 1983-1993 period. The nature of alien criminality is evaluated in terms of nationality type, self-reported crime, crime among adults, and victims of violence. Research on the social situation of immigrants and their adaptation to a new society is reported, and phases of the adaptation process are identified. Traumatic experiences caused by political and social changes are examined, as well as the economic and social adaptation of immigrants. The link between the lack of social integration when immigrants first arrive in Sweden and criminality is considered, and the importance of organizing crime prevention work with immigrants across a broad front that promotes the identity and self-esteem of immigrants in a new society, reinforces self-control, and considers counteracting forces within the community is emphasized. 33 references and 3 figures