We begin by stating the obvious. A decline in fertility rates as large as that which occurred in North America in the 1960s and 1970s must have profound economic consequences. The decline in the population growth rate and the continuing shift in population age structure ultimately must affect every aspect of the macroeconomy- the rate of growth of the labour force and of the economy's productive capacity, the level and composition of consumer demand, the rate of investment and its allocation among economic sectors, the demand for public services, and so on. Some effects - school enrollment effects, for example - have been evident for many years. Others, such as labour force effects, are now upon us. Still others, such as the future social security implications of an aging population, have yet to be experienced, but can be foreseen with some clarity, at least in broad outline. However, many of the economic implications of the transition from very high to very low fertility rates are not as clearly discernible. Moreover, demographic influences may take an extremely long time to work themselves out. The effects to date of the fertility shock are, in a sense, just the tip of the iceberg. There is much more to come as the economy adapts to the evolving size and age structure of the population over the decades ahead.