This study examined the continued gender imbalance in mathematics participation in senior high, which has implications for adolescents' future careers. It confirms persisting greater male participation in maths-related educational and occupational choices among this sample of Australian youth. Gendered course-taking in maths, along with participation intentions for maths-related careers, were explained using the Expectancy–Value framework of Eccles and colleagues (Eccles (Parsons) et al., 1983; Wigfield & Eccles, 2000). The influences of maths-related self-perceptions, intrinsic and utility values, and perceived task difficulty were assessed using longitudinal data from a sample of 442 adolescents spanning Grades 9 through 11 in Sydney, Australia. Gendered maths-related self-perceptions and intrinsic values were the major influences on gendered educational participation in senior high maths, which subsequently predicted maths-related career aspirations—over and above prior mathematical achievement. Utility value showed a curvilinear relationship with maths-related occupational intentions moderated by gender, whereby girls with the highest utility values planned for highly maths-related careers, while boys with mid through high utility values planned similarly highly maths-related careers. Recommendations focus on ways to enhance participation in maths, especially for girls.