Little prior research exists on the achievement motivation of Mexican American students. In a rural south Texas junior high school, 120 eighth-grade students completed the 1969 Achieving Tendency Scales and demographic and socioeconomic questionnaires. Subjects were equally divided among four groups: Mexican American males and females and Anglo American males and females. Two months later, 23 subjects were interviewed about their responses. There were no significant ethnic or gender differences in achievement motivation scores, but there was a large range of scores within each of the four groups. Analysis of interview responses revealed differences between students with a strong motivation to achieve and those with a strong motivation to avoid failure. Subjects with a stronger motivation to achieve were generally more interested in learning, more willing to take risks, and higher in self-confidence and self-esteem; subjects with a stronger motivation to avoid failure feared making mistakes, feared parental or other adult disapproval, and doubted their ability to complete difficult tasks successfully. The two groups were not always different in their grades or standardized test scores, but they were consistently different in their attitudes and their approaches to school work. (Contains 19 references.) (SV)