Soc Psychiat Epidemiol (2010) 45:639–646 DOI 10.1007/s00127-009-0105-6 O R I G I N A L P A P E R Maike Gieling Æ Wilma Vollebergh Æ Saskia van Dorsselaer Ethnic density in school classes and adolescent mental health Received: 5 February 2009 / Accepted: 15 July 2009 / Published online: 5 August 2009 The Author(s) 2009. This article is published with open access at Springerlink.com Abstract Objective The present study set out to examine the association between ethnic composition of school classes and prevalence of internalising and externalising problem behaviour among ethnic minority and majority students. Methods Data were derived from the Dutch 2002 Health Behaviour in School-aged Children (HBSC) survey, a nationally representative cross-sectional study with a total of 5,730 adolescents, aged 11–18 and attending secondary school, of which 931 belong to ethnic minority groups. The data were analysed using a multilevel regression model. Results The study revealed that, after taking individual characteristics like age, gender, educational level and family afﬂuence into account, ethnic minority students on average report higher levels of externalising but not inter- nalising problems. Ethnic density on the level of school classes modiﬁed this difference, as a negative association between the proportion ethnic minority students in class and externalising problem behaviour was found, but only for ethnic minority students. No effect of ethnic composi- tion was found with respect to internalising problem behaviour. Conclusion The data revealed that ethnic minority stu- dents report higher levels of externalising problem behav- iour, but only in classes with a minority of ethnic minority students and not in classes with a culturally diverse M. Gieling (&) W. Vollebergh Faculty of Social and Behavioural Sciences, Utrecht University, Heidelberglaan 2, 3584 CS Utrecht, The Netherlands e-mail: m.gieling@uu.nl S. van Dorsselaer Trimbos Institute (Netherlands Institute of Mental Health and Addiction), Da Costakade 45, 3500 AS Utrecht, The Netherlands composition. This points towards a possible beneﬁcial effect of a more culturally diverse environment for minority students. Majority students appeared to be insensitive for the ethnic density effect. Future studies should investigate the role of the ethnic composition of the school class more in-depth. Keywords Internalising problems Externalising problems Ethnic density School-related context Multilevel Introduction The multicultural society is a much-debated topic in con- temporary Western Europe. The challenge to accommodate large numbers of immigrants with a variety of cultural and religious backgrounds has received a great deal of attention in politics, media and science. With respect to the psy- chological well-being of immigrant and ethnic minority adolescents, the number of large scale studies in Europe is limited [3, 14, 28–30]. Furthermore, little attention is paid to the relation between contextual factors and mental health among these adolescents. The central question in the present study was whether the presence of other ethnic minority youth in the direct social context is related to the prevalence of internalising and externalising problem behaviour among ethnic minority students. Several studies have revealed that ethnic minority youth in the Netherlands is at higher risk for the development of internalising and externalising problems [18, 24, 31]. However, as several studies on the ethnic density effect have successfully argued, the use of ethnicity as a risk factor confounds ethnic group membership with minority status [20]. The ethnic density hypothesis suggests that 123