In order to conduct a sociolinguistic analysis of language acquisition, data were collected on one bilingual child's speech through diary notes and tape recordings made at regular intervals from birth to age 5, with special attention given to contextual information related to each speech event. The child's languages include Spanish, English, and a passive knowledge of Italian. Observations drawn from the data and analyses suggest that the child begins differentiation almost immediately on contact with the two language systems, that this differentiation is facilitated by the separate use of each language in the environment, and that the child is capable of complete code switching as early as 2 years, 8 months. Conclusions stress the effect of social variables on language choice, the influence of the caretakers' role on the child's developing verbal behavior, and the existence of differentiated language styles as an early development in child speech. (Author/JM)