Why do fertility rates vary so much across countries? Why are European fertility rates so much lower than American fertility rates? To answer these questions we extend the Barro—Becker framework to incorporate the decision to accumulate human capital (which determines earnings) and health capital (which determines life span). We find that cross-country differences in productivity and taxes go a long way toward explaining the observed differences in fertility and mortality.

The authors study the problem of optimal taxation in three infinite-horizon, representative-agent endogenous growth models. The first model is a convex model in which physical and human capital are perfectly symmetric. The authors' second model incorporates elastic labor supply through a Lucas-style technology. Analysis of these two models points out the danger of assuming that government expenditures are exogenous. In their third model, the authors include government expenditures as a productive input in capital formation, showing that the limiting tax rate on capital is no longer zero. In numerical simulations, they find similar effects on growth and welfare in all three models. Copyright 1993 by University of Chicago Press.