Abstract We examine the impact of population distribution on fertility in a nationally representative sample. We exploit detailed life-history data to conduct an event-history analysis of transition to first birth, examining mechanisms that might link migration and fertility: socialization, adaptation, selection, and disruption. Our multivariate analysis examines various socio-demographic traits, the place of birth, and interregional migration. Differences by region and migration stream are partly explained by compositional factors, such as female employment, union type, and education. The analysis presents much evidence for demographic selection and socialization and less for adaptation or disruption. The persistence of the region of origin differentials points to the continuing importance of the context. 1. Introduction The effect of the place of residence and migration on fertility has been a long-standing concern in population studies (White et al. 1995, Chattopadhyay et al. 2006). This observation assumes a particular importance in Italy, a country that in the 1990s had the lowest fertility in the world and remains characterized by very low fertility (Billari and Kohler 2004). While the emergence and persistence of nations with 'very low' or 'lowest-low' fertility has often been noted (Kohler et al. 2002, United Nations 2006), the persistence of regional differentials in the level of fertility and the pace of change is scrutinized less often. Italy, moreover, remains characterized by the strong redistribution of the population inside its territory (Bonifazi and Heins 2000). This process involves both men and women of working and reproductive ages. Redistribution takes place among areas marked by sizable differences in demographic, economic, and social patterns. Our motivation for this paper comes from a growing concern in demography for a better understanding of context in fertility outcomes. In this paper, we examine the relationship between population distribution (context as place) and fertility. We allow for the region of birth and migration itself (origin-destination combination) to influence childbearing outcomes. In addition to speaking to current concerns, we extend a longstanding literature investigating the way in which fertility is conditioned, in part, by migration and geographic setting. The influence of place and migration on fertility has been subject to numerous prior studies. Such studies draw on several potential mechanisms that might give rise to an association between migration and fertility: socialization, adaptation, selectivity, and disruption (Caldwell 1982). We discuss the relevance of these in the model we propose and investigate. In this paper, we emphasize the way in which changes in the predictive power of covariates help shed light on these mechanisms. We cannot fully disentangle all mechanisms, precisely because some characteristics remain unmeasured.4 We say less about disruption, because it is less likely to operate in a high-income setting (such as contemporary Europe) and, in fact, we find less empirical evidence for it. Our approach analyzes the impact of geographical mobility and residential location on fertility in a large nationally representative sample of Italian women. We use longitudinal data drawn across several waves and with retrospective information. We examine the effects of age and cohort variables, several individual traits, the characteristics of the origins and potential destinations, and the migratory event itself. In so doing, we test for the influence of geography and migration, and also examine the applicability of some existing theories on this topic to the Italian setting. 2. The Italian situation - an overview The dynamics of fertility and internal mobility in Italy are very well-known phenomena. Although an appreciable literature describes these processes, we review some regional trends in order to shed light on their interconnections and to demonstrate the value of a comparative approach. …