BACKGROUND According to classic demographic transition theory, mortality change is the key factor that triggers a decline in fertility. Research on this topic has mostly relied on aggregate or time series data. Since fertility is based on the joint decisions of couples when confronted with specific fertility-childhood mortality outcomes, a focus on the experiences of individual couples is needed. Recently, Reher and Sanz-Gimeno used this approach to analyze individual longitudinal data for the Spanish town of Aranjuez. OBJECTIVE We investigate whether, in a country and in populations characterized by varying cultural and socioeconomic circumstances, family organization, and demographic regimes, the same mechanisms influenced the process of fertility decline as in Spain. METHODS The study uses micro longitudinal data from the Historical Sample of the Netherlands for a period stretching from the last quarter of the 19th century to the middle of the 20th century, and demographic measures identical to those used in the Spanish study to test whether the decline in fertility was triggered by the decline in mortality at the level of the family. As religious groups and social classes differed in their ability to correctly assess the implications of mortality levels, and in their willingness, readiness, and ability to react to these changes by adapting their reproductive behavior, we also compared the effect of mortality decline by the religion and the social class of the couples. RESULTS We observed that childhood survival had clear effects on reproduction, the chances of having another child, and the length of the intervals between births, which indicates that this variable was crucial for fertility decisions. This pattern was especially strong after 1900. There were rather consistent and expected differences in the reactions to the survival of children by social class and religious group. Whereas skilled workers were rather sensitive to the number of surviving children, farm families were much less likely to allow ...