Purposes of this study were to detect some of the sociocultural differences between Mexican American and Anglo junior high school students; to determine how the sociocultural characteristics of the Mexican American students were related to their language background; and to ascertain how characteristics of both groups were related to their achievement. The sample consisted of 126 male and female students, 87 of whom were Mexican American. Scales were developed from questionnaire and interview data to measure language background, self-concept of ability, achievement orientation, parental independence training practices, parental achievement pressure, social distance, and socioeconomic status. Student achievement was measured both by English and mathematics grades and by standardized tests. Observed sociocultural differences between Mexican American and Anglo students appeared to be due to ethnic backgrounds and socioeconomic and other social conditions associated with this background. Mexican American students exhibited many of the characteristics of the culture of poverty described by Oscar Lewis. Part of the depressed achievement of Mexican Americans, when compared to Anglo students, can be attributed to their lower self-concepts of ability; fatalistic, present-time orientation; non-democratic independence training experiences; and high religious social distance. (Author/LS)