This study uses Fehr, Jokisch, and Kotlikoff?s (2004a) dynamic general equilibrium model to analyze the effects of changes in fertility and mortality on the developed world?s demographic transition. The model features three regions – the U.S., Japan, and the EU-15 – and incorporates age- and time-specific fertility and mortality rates, detailed fiscal institutions, and international capital mobility, subject to adjustment costs. Our simulations confirm the offsetting fiscal and economic consequences of both higher fertility and lower mortality rates. The simulations indicate very minor effects on the developed world?s rather bleak baseline transition path from either major increases in fertility rates or major reductions in mortality rates.