Ethnic differences in violent behavior can be found in official crime statistics, as well as in surveys on juvenile delinquency. To explain these differences, research mainly focuses on factors like parental violence, violence legitimizing norms of masculinity, or socio-economic status. Little research has examined the role of friendship network's ethnic composition on ethnic differences in violent behavior, although different sociological and criminological theories suggest that the composition of friendship networks can play an important role for attitudes and behavior of its members. Using data of a survey conducted in 2006 among all ninth-grade pupils in Hanover (Germany), we investigated the influence of friendship network's ethnic composition on violent behavior in general, and on ethnic differences in violent behavior in particular. Due to the specific sampling procedure, it was also possible to look for neighborhood effects both on (ethnic differences in) juvenile delinquency and friendship network composition. Findings indicate that there are significant differences in the network composition across the ethnic groups. After controlling for these network characteristics, ethnic differences in violent behavior disappeared. Furthermore, the results show that the friendship network's ethnic composition also depends on community characteristics. (Contains 3 tables, 1 figure and 4 notes.)