We analyze the effect of fertility on income per capita with a particular focus on the experience of Europe. For European countries with below-replacement fertility, the high cost of continued low fertility will only be observed in the long run. We show that in the short run, a fall in the fertility rate will lower the youth dependency ratio and increase the working-age share, thus raising income per capita. In the long run, however, the burden of old-age dependency dominates the youth dependency decline, and continued low fertility will lead to small working-age shares in the absence of large immigration inflows. To illustrate these effects we construct a population accounting model and simulate steady-state outcomes. Regression analysis indicates the differing marginal effects of long-term fertility change in Europe versus the rest of the world.