Just as in the United States, Europe has a strong history of migration. In Europe, migration has specific political, economic, and cultural roots. Changes in Europe that have promoted migration include the need for a workforce in the expanding Western European economies, a substantial influx of refugees and asylum seekers in many European countries due to global instability, and population changes after the fall of the Berlin Wall. As a result, European countries have many young residents who are second-generation ethnic minorities, and large cities have become more multicultural. Population change and the availability of images of gang culture through modern media have created a breeding ground and model for gangs. European gangs are not all alike, nor are the gangs with members from particular countries. Still, it is possible to draw several conclusions about the relationship between migration and gangs in Europe, about the characteristics of this relationship, and about the impact migration has on gangs. One of the most important issues is the role that social marginalization theory plays in understanding the influence of migration in gang formation. Preliminary evidence indicates that isolation from mainstream institutions and behavior promotes gang formation and antisocial behaviors. Other issues that must be addressed include the influence of socioeconomic conditions on gang emergence in certain neighborhoods, the extent to which migration creates competition for territory and respect among ethnic groups, and whether the clustering of ethnic groups in the same neighborhoods exacerbates social isolation from the mainstream culture. The level of stigmatization attached to various migrant and ethnic groups may also be a factor in gang formation. 39 references