This talk examines how linguistic and national identities are co-constructed and are the site for discursive struggle in interaction– in particular, how they are affected by general socio-cultural patterns and ideologies, the topics under consideration, and the positioning of the interactants. This is shown through a fine-grained analysis of two interconnected conversations in French, the first between two monolingual French speakers and one French-(American) English bilingual, the second including a third monolingual French speaker. Shifts in the linguistic and national identities of the bilingual are examined in relation to the linguistic and symbolic capital of the third French speaker, who has negative prejudices and stereotypes about the U.S., seizes power in the interaction, and causes the bilingual to change his linguistic identity in the second conversation as against the first, and to alter his national identity in the course of the second conversation. The shifts are shown through identity acts (a sub-type of speech acts) and are indexed by the use of, in particular, indefinite/non-specific pronouns.