This study focuses on educational attainment in New Zealand's undergraduate programmes in medicine and science (N = 750 and N = 4722, respectively), by following four student cohorts over the course of their degree. This research aimed to identify the extent to which studying in competitive academic programmes (Medicine and BSc) attenuate educational disparity related to schools' socio-economic backgrounds. We found that Science students coming from the lowest Socioeconomic Status (SES) schools had lower attainment in their first tertiary year but their achievement improved throughout the programme while outperforming all other students in their third year. However, medicine students from lowest SES schools had lower attainment in their first year but from their second year, their attainment was not significantly different from their counterparts coming from higher SES schools. This study's findings, support the selection processes for these programmes, allowing students from disadvantaged secondary schools to enrol and succeed in competitive academic programmes.