At present, little is known about the welfare of very young immigrant children, since the emphasis thus far has been on the integration of school-aged children and youths into host societies. This study seeks to redress this research gap by synthesizing existing research on both the children of immigrants and early childhood development. It asks two questions. First, is there a nativity gap between the second and third-plus generations in their school readiness measured in terms of reading and receptive comprehension skills, during their preschool years? Second, if it exists, which factors account for this nativity gap – family resources, childcare arrangements, or neighborhood contexts? In asking the latter question, this study strives to add a distinct sociological perspective to the study of the second-generation during early childhood. Based on analysis of Waves 1, 3 and 5 of the Fragile Families Study of Child Well-being, I find mixed evidence for the existence of a nativity gap in cognitive outcomes. In terms of receptive vocabulary skills as measured by the Peabody Picture-Vocabulary Test (PPVT), I find that a significant second-generation disadvantage does exist and it appears to have widened over time between the ages of 3 and 5. However, in terms of word recognition as measured by the Woodcock-Johnson Letter-Word Identification Test (WJ-LWIT), there appears to be no significant difference. Further post-estimation tests show that this is not simply due to a discrepancy in the construction validity of these two instruments; instead, the different results are a function of the tests' different objectives given that the PPVT measures receptive vocabulary skills while the WJ-LWIT measures reading skills. The implication is that the second-generation enter the classroom with a disadvantage but only in terms of certain skills. Given that there is a significant second-generation disadvantage for receptive vocabulary skills, I probe further into the institutional mechanisms through which this disadvantage operates. Net of demographic characteristics, family resources matter a lot in explaining the nativity gap in receptive vocabulary. Compared to the role of family resources, childcare arrangements and neighborhood contexts do not appear to directly reduce the nativity gap, once demographic characteristics and family resources are accounted for. That is not to suggest that they do not matter. Instead, given that these factors are highly correlated with the amount of family resources available to children, it is likely that all these factors operate in tandem to produce a significant nativity gap.