A study of a two-way bilingual program in the Port Chester, NY Public Schools examined the relationship between classroom environment, and the language proficiency levels and second language learning outcomes of bilingual and monolingual pupils participating in the program. Pupils were second- through fifth-graders, including native-Spanish-speaking, limited-English-proficient (LEP) pupils, and proficient native-English-speaking pupils. The instructional outcomes investigated include English and Spanish language proficiency, and academic achievement in mathematics. Data sets were collected between 1984 and 1987. The classroom environment was assessed by student perceptions of the degree of satisfaction, friction, competitiveness, difficulty, and cohesiveness in the classroom. Analysis of the data confirms the important role of classroom environment and language proficiency in bilingual and second language learning for elementary school children. For each year of the two-way program, students perceptions of their classroom environment influenced their growth in learning a second language. (MSE)