A study examined the acquisition of negation in English as a Second Language in a 4-year-old Salvadoran girl, a native speaker of Spanish. Specifically, the study looked for evidence of language transfer in bilingual acquisition and the direction of that transfer (Spanish to English, English to Spanish). Over 5 months, spontaneous speech (55 samples) was recorded in several natural settings (school, home, and restaurant) and an imitation task method was used to elicit additional language samples (n=100). The syntactic structures studied were negative-verb sequence, "do" inclusion in the verb form, and sentence subject omission. These data were also compared with data from a previous study of monolinguals and bilinguals of the same age. Results indicate that in the case of the first two structures examined, the child had internalized the rules of Spanish negation well enough to influence the use of Spanish negative structures in her English constructions. In the case of sentence subject omission, findings did not indicate a Spanish influence, but rather that she had acquired enough English rules on sentence subject inclusion to influence her use of this structure in both Spanish and English, suggesting a two-way transfer effect. (MSE)