Designed to develop over five years a model bilingual program for nursery school through grade 6, the demonstration program provided early bilingual education intervention to facilitate the simultaneous learning of two languages and thus develop the cognitive, affective, and psychomotor skills of children with limited English speaking ability from low income Mexican American families. External evaluation of the program's fourth year, 1978-79, measured the program's impact on the achievement of the 85 participants in grades 2-5 in the areas of language arts, reading, mathematics, and Spanish language development. Based on comparison of participants' scores on the Comprehensive Test of Basic Skills with those of a control group (55 students), the program generally met its objectives of having participating students with low English proficiency skills (LEPS) and "other" bilingual students equal the control group's achievement in reading, math, and English language skills at grade levels 2-5. "Other" bilingual students had lower scores in all areas at the second grade level and in reading at the third grade level. Analysis of LEPS participants' scores on the Peabody Picture Vocabulary Test revealed a significant gain in Spanish language skills at all grade levels. Additional remedial aid was recommended for "other" bilingual students in all areas at the second grade level and in reading at the third grade level. (SB)