Abstract
This paper investigates the determinants of school friendship networks among adolescents, proposing a model of network formation and estimating it using a sample of about 10,000 secondary school students in four countries: England, Germany, the Netherlands and Sweden. We test the idea that networks arise according to homophily along many characteristics (gender, school achievement and ethnic and cultural backgrounds), and assess the relative importance of each factor. In addition to gender, we find that country of origin, generational status and religion predict friendship for foreign-born students. For individuals born in the survey country, ties depend on a broader set of factors, including socioeconomic status and school achievement. In sum, homophilic preferences go considerably beyond ethnicity. Multiculturalism, which gives prominence to ethnic backgrounds, risks emphasising the differences in that dimension at the expense of affinity in others.