The plans that adolescent boys and girls make about participating in senior mathematics courses and mathematics-related careers are often at odds with their actual mathematics achievements. In contrast to explanations relating plans to gender differences in mathematics performance, mathematics participation can be explained by expectancy-value models of academic choice, based on gendered self-perceptions, task perceptions, and value judgments. This study with Year 10 Australian students (N= 199) added to an expectancy-value model the students' current course levels that act as salient social categories. The results suggest that intervention programs need to target perceptions by girls and boys about mathematical talent, as well as making mathematics more useful and interesting to young adults. The findings raise further questions about the stratification of students into separate mathematics courses during the early years of high school.