The Education of Hispanic students, particularly in mathematics, continues to be a pressing issue. Language factors such as bilingualism and limited-English proficiency play important roles in Hispanic achievement in general; however, the influence of language factors on the development of mathematical meanings for this population has yet to be studied in detail. The purpose of this project is to investigate linguistic factors (Spanish and English) which help or hinder the acquisition of mathematical knowledge and understanding. This project will conduct an ethnographic study of mathematics teaching in four elementary classrooms with students of varying levels of English proficiency. The objective is to gather contrastive data based on teacher-student interaction during mathematics instruction. Data analysis will be guided by theoretical frameworks drawn from research on mathematics teaching, on teacher discourse and the development of meaning, and on bilingual learners. The results will be disseminated to both researchers and practitioners and will contribute to our understanding of the teaching of mathematics in general and the improvement of instruction for Hispanic students, in particular.