Mexican and Mexican American students enrolled in 58 bilingual settings (grades K-6) were studied to determine whether there was a relationship between student achievement and specific ethnic and profile characteristics of students and teachers. Five student-related independent variables were based on language dominance. Teacher-related independent variables were cooperative response, teacher training, ethnicity, and grade level taught. A significant relationship existed between cooperative response and achievement of Mexican and Mexican-American students in the areas of reading and mathematics. Mexican and Mexican-American students responded negatively to a cooperative teacher in the lower grades (K-2) and positively in the upper grades (3-6). Students responded positively to the competitive teacher in the earlier grades and negatively to the competitive teacher in the upper grades. Influence, both positive and negative, was at the 5% level of significance. A bilingual setting with a bilingual Chicano teacher yielded positive results in reading and mathematics. Systematic differences in social motivations and learning styles existing between ethnic student populations also seemed to contribute at a significant level. (Author/CM)