The author discusses the nature of in-group bias and the social motives that underlie ethnocentric attachment to one's own membership groups. Two common assumptions about in-group bias are challenged: that in-group positivity necessitates out-group derogation and that ingroup bias is motivated by self-enhancement. A review of relevant theory and research on intergroup relations provides evidence for three alternative principles: (a) in-group attachment and positivity are primary and independent of out-groups, (b) security motives (belonging and distinctiveness) underlie universal in-group favoritism, and (c) attitudes toward out-groups vary as a function of intergroup relationships and associated threats to belonging and distinctiveness.