The study examined the effects of socioeconomic origin (SES) and mental ability (MA) on levels of educational (EA) and occupational aspiration (OA), academic performance (AP), and significant others' influence (SOI) for 1,950 5th grade elementary and 4th year gymnastic students in Rio Grande do Sul, Brazil. Representative samples of approximately 250 students were drawn at each level from 4 counties varying by the physical presence of higher educational institutions. Assumptions buttressing the model were questioned for this sample, and effects of SES and MA on the performance variables were hypothesized to vary by grade level. Specifically, it was hypothesized that due to the heavy screening of students by SES prior to the secondary level, the effect of MA would increase and that of SES decrease at the gynasium level. It was further hypothesized that AP and SOI would exercise more important roles as intervening variables between SES and MA, and the aspiration variables at the gymnasium level. Data were obtained from closed-ended questionnaire items; where operational equivalents were impossible to use or were deemed less appropriate, functional equivalents were used. Working hypotheses were tested using path and path regression coefficients. SES was found to increase in importance as a determinant of EA and OA, and the mediating effects of SOI and AP between SES and EA decreased at the gymnasium level. (Author/NQ)