What caused the baby boom? And can it be explained within the context of the secular decline in fertility that has occurred over the last 200 years? The hypothesis is that: (a) The secular decline in fertility is due to the relentless rise in real wages that increased the opportunity cost of having children; (b) The baby boom is explained by an atypical burst of technological progress in the household sector that occurred in the middle of the last century. This lowered the cost of having children. A model is developed in an attempt to account, quantitatively, for both the baby boom and bust.

Powerful currents have reshaped the structure of families over the last century. There has been (1) a dramatic drop in fertility and greater parental investment in children; (2) a rise in married female labor-force participation; (3) a significant decline in marriage; (4) a higher degree of positive assortative mating; (5) more children living with a single mother; and (6) shifts in social norms governing premarital sex and married women’s roles in the workplace. Macroeconomic models explaining these aggregate trends are surveyed. The relentless flow of technological progress and its role in shaping family life are stressed.