A higher proportion of students are privately educated in Australia, compared with many other nations. In this paper, we tested the assumption that private schools offer better quality education than public schools. We examined differences in student achievement on the National Assessment Programme: Literacy and Numeracy (NAPLAN) between public, independent, and catholic schools. Cross-sectional regressions using large samples of students (n = 1583-1810) at Years 3, 5, 7 and 9 showed few sector differences in NAPLAN scores in any domain. No differences were evident after controlling for socioeconomic status and prior NAPLAN achievement. Using longitudinal modelling, we also found no sector differences in the rate of growth for reading and numeracy between Year 3 and Year 9. Results indicate that already higher achieving students are more likely to attend private schools, but private school attendance does not alter academic trajectories, thus undermining conceptions of private schools adding value to student outcomes.