A gap exists between studies of gender and language and studies of bil
ingualism. The considerable attention given by studies of discourse st
yle to gender differences in friendship patterns is not reflected in r
esearch on bilingual communities. This ethnographic case study of high
school students in the Barcelona area shows that gender differences i
n peer group structure can affect the use of the bilingual repertoire,
even when there are no apparent sex differences in second language ac
quisition. In this setting, girls' friendship circles are more solidar
y and cohesive than boys'. Moreover, girls' groups are ethnically and
linguistically homogeneous, while boys' social circles can be ethnical
ly mixed and internally differentiated linguistically. Girls' friendsh
ips set stronger constraints on language behavior. In turn, boys and g
irls reap different social benefits and costs for their linguistic cho
ices, with more serious consequences for girls' social identities and
acceptance by peers.