As the younger generation in Vietnam increasingly switches between the English and the Vietnamese languages, numerous linguistic and sociocultural strictures arise. Foregrounding the preservice English-language teachers of this generation, this article locates them in a dilemma between the discourse of globalization and their code-switching practices, on the one hand, and the moral-guide duty they are expected to fulfil within the discourse of linguistic nationalism on the other hand. Drawing on a case study conducted with survey questionnaires (N = 483) and focusing on interviews and focus groups (N = 15), this article reports the confusion, the decisions, and the negotiations made by different preservice teachers as they were faced with this dilemma. Particularly underlining the theme of negotiation, the article proposes certain changes to the English-language-teacher training curriculum in Vietnam.