An event-history analysis of ten rural villages in Spain from 1750 to 1949 indicates that the likelihood of parents having additional children was influenced by the number of their surviving children and the children’s sex composition. Parents whose children had a low survival rate had more children than parents whose children generally survived. Exclusively having daughters during the pre-transitional period also reflected, to a limited degree, the likelihood of new conception. The results suggest that some families adapted their reproductive behavior to their desired objectives. In the pre-transitional period, as well as during the transition itself, decisions to control or encourage fertility often appear to have been based on family size and composition.