The effects of a cooperative learning program, Bilingual Cooperative Integrated Reading and Composition (BCIRC), on the Spanish and English reading, writing, and language achievement of second and third graders of limited English proficiency in Spanish bilingual programs in El Paso (Texas) were studied. BCIRC was expected to improve student achievement during the transition from Spanish to English by giving students daily opportunities to use language to find meanings and solve problems, and by applying well- established principles of cooperative learning to increase student motivation and achievement. A comparison of standardized test scores in three BCIRC and four comparison schools generally supported these expectations. On the Spanish Texas Assessment of Academic Skills, second graders scored significantly better than comparison students in writing and marginally better in reading. On the English Norm-referenced Assessment Program for Texas third graders scored better than comparison students in reading, but not language. Third graders in BCIRC for 2 years scored better than control students on both scales, and BCIRC third graders met criteria for exit from bilingual education at a significantly higher rate than did comparison students. Qualitative evidence shows that students in cooperative groups are making meaning for themselves, enjoying the program and having success in writing contests. (Contains 6 tables and 43 references.) (Author/SLD)