The societal integration of immigrants is a great concern in many of today's Western societies, and has been so for a long time. Whether we look at Europe in 2015 or the United States at the turn of the twentieth century, large flows of immigrants pose challenges to receiving societies. While much research has focused on the socioeconomic integration of immigrants there has been less interest in their demographic integration, even though this can tell us as much about the way immigrants fare in their new home country. In this article we study the disparities in infant and child mortality across nativity groups and generations, using new, high-density census data. In addition to describing differentials and trends in child mortality among 14 immigrant groups relative to the native-born white population of native parentage, we focus special attention on the association between child mortality, immigrant assimilation, and the community-level context of where immigrants lived. Our findings indicate substantial nativity differences in child mortality, but also that factors related to the societal integration of immigrants explains a substantial part of these differentials. Our results also point to the importance of spatial patterns and contextual variables in understanding nativity differentials in child mortality.