Presented is a study reporting the findings relevant to the amount of variation of eleventh- and twelfth-grade students in taking science courses. The findings are reported in terms of ability level (I.Q. scores), socio-economic status (father's occupation), eighth-grade academic grade-point average, and specific science grade in the eighth grade. The magnitude of the contribution of sex role in predicting eleventh- and twelfth-grade entry into science courses, alone and when combined with I.Q., and socio-economic status and achievement in eighth grade are discussed. (Author/SA)