Students' post-school options are limited if they have not completed mathematics subjects involving the study of calculus. This paper employs a sociocultural approach to identify institutional practices that might promote sustained engagement with these subjects among students from disadvantaged backgrounds. Drawing on interviews with mathematics teachers and the school guidance counsellor, six themes emerged as potential institutional practices contributing to increased enrolments: curriculum organisation across year levels, staffing of mathematics classes, culture of the Mathematics Department, STEM program, and provision of appropriate tasks and resources.