There has long been a debate about the role of cultural and institutional factors in shaping fertility behavior. However, neither economic theories nor those based on the Second Demographic Transition have been completely satisfactory in explaining the differences in levels and trends in fertility among European countries. This paper contributes with a joint consideration of both cultural and structural macro contexts. Following an epidemiological approach, we investigate how fertility behavior is shaped by institutional factors in the receiving countries by taking into account immigrants' cultural background. Using data on EU internal migrants from the six available rounds of the European Social Survey, we employ cross-classified multi-level regressions to account for the complex data structure of different sending and receiving countries. We find that both traditional values and generous expenditure for families are positively associated with the number of children. More interestingly, the interaction between these factors shows that the cultural effect of traditionalism values persists only in countries characterized by a lower investment in family policies –i.e., Mediterranean countries. This appears to be partially explained by educational level as well as by women's labor market participation.