A group of Mexican-American children living in a small Illinois town were observed to study the acquisition of communicative competence. The children's spontaneous and elicited narratives showed combinations of Spanish and English. If three stories represented here are considered syntactically, none involves random alternation of codes. Almost all switches involve entire sentences. In spontaneous narratives, there is much less code-switching than in the elicited stories. English stories contain almost none, Spanish only a little switching. Switching primarily involves nouns, or marks quotations. Asides to the audience or expression of special ideas may cause a language switch. Code-switching seems to follow a pattern, and language dominance may explain why switching to find the right word is more prevalent when speaking Spanish than English. (CHK)