A recent increase in the number as well as the breadth and depth of historical studies of European fertility permits new insights into the causes and nature of fertility decline. The historical experience suggests that fertility declines in Europe took place under a wide variety of social, economic, and demographic conditions and that cultural setting influenced the onset and spread of fertility decline independently of other factors. The practice of family limitation within marriage was rare prior to the decline in fertility even though a substantial portion of births may have been unwanted. Yet, once under way, increases in the practice of family limitation and the decline of marital fertility were essentially irreversible processes. Evidence behind each of these conclusions is described and their implications for population policy in the developing world are indicated.