An ethnographic study of language proficiency in the home and school languages of bilingual children was conducted. From a qualitative sociolinguistic perspective, language proficiency, the relation of linguistic performance to community language use and attitudes, and the correlation of the sociolinguistic findings on language repertoire with widely used current tests were investigated. Using microethnographic techniques, data were collected on six third-grade Hispanic children in classroom, home, and community settings. Information related to language use, language proficiency, and attitudes toward language, bilingualism, and bilingual education was obtained through a questionnaire. An ethnographic description of the relationship among community data, parents' data, and children's language proficiency is presented. Using the language repertoire collected, the congruency between actual language collected from the children and the test content in the Bilingual Syntax Measure and James Language Dominance Tests was analyzed. Finally, a functional analysis of questions and directives found in the children's repertoire in both Spanish and English was conducted. The survey instrument is appended. (Author/RW)