In this paper we interrelate different theories of identity and describe how various social contexts and cognitive motives influence the process of identity change. We consider two competing theories about the linkage of contexts with motives for identity change: the effect of category traits, based on social identity theory, and the effect of social networks, based on identity theory. To explore these relations, we use data collected on more than 6,000 adolescents at six high schools in two consecutive school years. Multilevel logit models reveal a strong relationship between contexts and perceived identity imbalances, and a strong effect of identity imbalance on identity change. More important than category traits are the social network characteristics of prominence, homogeneity, and bridging; these form social contexts that affect perceptions of identity imbalance, and the perceptions in turn lead to a heightened incidence of identity change. (Contains 1 figure, 8 tables, and 16 footnotes.)