Although research on the primary and secondary effects of social origin aims at understanding the relative importance of performance and choice in educational decision making processes, it tends to downplay that primary effects are a function of two separate components: (a) the level of social inequality in academic per-formance and (b) the effect of academic performance on educational decisions. Examining trends in educational inequalities in Denmark from 2002 through 2016, I demonstrate that separately considering these two com-ponents leads to new interpretations of why social class inequalities in educational decisions change over time. I find that although both primary and secondary effects of social origin are declining in Denmark over the period, the decline in primary effects occurs in spite of increasing social class gaps in academic performance. In contrast, the decline results from decreasing educational returns to academic performance. My findings suggest that conventional comparisons of primary and secondary effects of social origin across contexts such as countries or time periods may mask the pathways through which social class differentials in educational decisions arise.