This paper explores the fertility decisions of Canadian immigrants using a 20 percent sample of the Canadian Census of Population for the years 1991 through 2006. We focus on those individuals that migrated as children and on their age at arrival to assess their process of assimilation in terms of fertility. Our analysis does not show any sharp discontinuity in fertility by age at migration as sometimes observed on education or labor market outcomes. Instead, there is an inverted U shape relationship between age of migration and immigrant fertility, with those migrating in their late teens having the highest fertility rates when compared to natives. This pattern appears among migrants from all origins - although their fertility levels differ. Results suggests that language acquisition is not a key mechanism through which age at immigration affects fertility - fertility behavior of immigrants with an official mother tongue also differs from that of natives. Rather fertility assimilation seems to be associated with education decisions. College graduates arriving to Canada anytime before adulthood behave as their native peers.