This paper focuses on the role of the home countrys birth rates in shaping immigrant fertility. We use the German Socio-Economic Panel (SOEP) to study completed fertility of first generation immigrants who arrived from different countries and at different time. We apply generalized Poisson regression to account for the underdispersion of the dependent variable. The results favor the socialization hypothesis holding that immigrants follow childbearing norms dominant in their home countries. We find that women from countries where the average birth rate is high tend to have significantly more children themselves. In addition, this relationship is the stronger, the later in life migration occurred.