We evaluate the effect of education policies, welfare programmes, technology and demographics on the differential evolution of the skill premium and on the rise in education investment in France and the US. We use a computable general equilibrium model with overlapping generations of individuals and endogenous education decisions. Human capital has two substitutable components - experience and education - both of which evolve endogenously over time. We use an original method to calibrate our model properly on the post-war period and run counterfactual experiments to assess the relative contributions of the different exogenous variables. The expansionary French education policy boosted the supply of skills and kept the skill premium low. In contrast, increasing education costs in the US contributed to increased wage differentials by reducing the rise in educational attainment. Skill-biased technical change is key to understanding rising school attendance and skill premiums in the US. It has a less important role and appears to be delayed in France.