The European Fertility Project had two objectives: (1) to create a quantitative record of the European fertility transition - the decline of 50% or more in the number of children the average woman bears. This profound demographic change, and the social changes associated with it, occurred within the past two centuries in almost all of the several hundred provinces of Europe, and (2) to determine the social and economic circumstances that prevailed when the modern decline in fertility began in the hope of elucidating the causal mechanisms of the fertility transition.