In this project we want to better understand the role of fertility choices in the context of the standard Urban Model. How many children will be born in each location? Why is fertility different across cities? What is the role of fertility for city growth, over and above migratory flows alone? How could the literature on fertility think for so long about long run trends without considering the impact of children on the equilibrium house price? What’s the impact of the increasing shift in household composition towards smaller households for the house price distribution of different cities?