This article examines the role of personality dispositions as determinants of people's reactions to threats to social identity. It is argued that since individuals characterized as high field-dependents have a greater tendency to anchor their identity in the social group than low field-dependents, they will be more affected by threats to social identity, especially when the context is framed as an intergroup context. Threat to social identity was manipulated by inducing intergroup similarity, and intergroup differentiation was measured. The first experiment assessed the hypothesis with minimal groups. The second experiment assessed it with real groups (two rival schools). Findings provided support for the hypotheses. The discussion centers on the role of personality dispositions in the social identity perspective.