Effective intervention into educational inequalities is dependent on having an accurate understanding of the factors which predict it. Research on the educational attainment gap between Indigenous and non-Indigenous youth in Australia has typically focused on closing the academic achievement gap in the hope that this will resolve the issue. However, recent research is beginning to find that Indigenous youth also have significantly different choice behaviours and resources. Using the work of Boudon, the current research used a Bayesian logistic regression model to explore the extent to which differences in university entry rates are due to achievement differentials (primary effects) versus differences in choice behaviours and resources (secondary effects) for Indigenous and non-Indigenous youth in Australia. This was applied to 10,000 Australian youth, followed over eight years. Results suggest that primary effects were predominant, however, a moderate proportion of the Indigenous university entrance rate gap is due to secondary effects.