Although the ideology behind curriculum differentiation presents it as a strategy for reducing educational inequalities, the research shows that, contrary to expectations, differentiation enhances inequalities. This may be a result of the stratified nature of most forms of curriculum differentiation that have been analyzed in existing research. Previous research has not looked into the implications of nonstratified curriculum differentiation on educational inequalities. This article attempts to fill this void by examining the effect of variations in subject offerings on gender and socioeconomic inequality in course taking and achievement in Israeli secondary education, where students can choose from among advanced courses that yield similar educational opportunities. Multilevel analysis was performed on 18,704 academic track students, distributed among 198 schools, who graduated in 1992. The main findings are as follows: Curricular differentiation is associated with increasing gender and socioeconomic inequality in course taking. When students can choose alternative subjects, boys and socially privileged students increase their concentration in advanced sciences courses. That concentration is accompanied by increasing inequality in achievement. The findings are interpreted, taking into account the constraints that ascriptive characteristics of the students pose on making curricular choices.