In 1985-86 Project MASTER an innovative Title VII program emphasizing language development through bilingual instruction in mathematics and science, served 640 students of limited English proficiency (LEP) at six elementary schools in the Bronx, New York. Most of the students were born in Puerto Rico, but many were from the Dominican Republic, Colombia, and several other Central and South American countries. The project, in its first year of a three-year funding cycle, emphasizes the use of both Spanish and English in the classroom in order to provide students with opportunities to transfer to English the communication skills they had acquired in learning their native language. At the same time, this approach enables students to master content-area subjects necessary for graduation. Parent participation and staff development activities formed an important component of the project, although the lack of a parent trainer limited the effectiveness of the parental involvement effort. Student performance on evaluation tests indicates the MASTER students made statistically significant gains in English and science, but students' scores in mathematics decreased from pretest to posttest. In general, the program's effectiveness could be improved if the project were staffed as originally proposed. Figures and statistical tables are included. (KH)