This article develops analytic links between cohort composition and human capital accumulation across generations. By focusing on cohort composition rather than cohort size, it offers new links between demographic change and economic outcomes. The model shows that changes in the educational attainment of parents and changes in relative fertility rates between educational classes affect human capital accumulation of the next generation. The main prediction of the model, of a negative behavioral feedback, is shown to be consistent with data on the probability of attending college for men born between 1927 and 1962.