More than a half century after its peak, the baby boom’s causes remain a puzzle. A new argument posits that rapid advancements in household technology from 1940 to 1960 account for this large increase in fertility. We present new empirical evidence that is inconsistent with this claim. Rapid advances in household technology began long before 1940 while fertility declined; differences and changes in appliance ownership and electrification in U.S. counties are negatively correlated with fertility rates from 1940 to 1960; and the correlation between children ever born (measured at ages 41 to 60) and access to electrical service in early adulthood is negative for the relevant cohorts of women. Moreover, the Amish, a group strictly limiting the use of modern household technologies, experienced a sizable and coincident baby boom. A final section reconciles this evidence with economic theory by allowing households to have utility over home-produced commodities that are substitutes for the number of children.