With this study I aim to understand the role of social networks of migration as very special catalysts of change in the countries of origin of important labor migration streams, particularly in the case of the emergent and second most important system of migration in which Latin Americans participate, i.e. the South European Migration System. I pursue this aim through the means of examining the characteristics and mechanisms of operation of ego – centered social networks of migration that are active within the migration streams from Argentina and Peru to Italy and Spain, therefore: (1) I examine the two different institutional contexts that contribute to the shape of the mentioned social networks of migration in Argentina and Peru; (2) I study the structure of these networks (which comprises characteristics such as size, density, and degree of heterogeneity); their resources and mechanisms of operation ; and (3) I discuss the main possible causal influences that these social networks of migration exert in the countries of origin of the emigration streams I study, namely Argentina and Peru, considering the very specific characteristics these social networks have in each one of the country cases. In order to discuss these causal influences, I examine their impact on children residing in Argentina and Peru who are members of migrant sending households, and I specifically analyze impacts on their living arrangements. I use quantitative and qualitative data on the emigration streams from Argentina and Peru to Italy and Spain which I collected during 2006, 2007 and 2008 , in Buenos Aires (Argentina) and Lima (Peru). Quantitative data was collected using a small household survey targeting relatives of migrants to Spain and Italy, in both cities (Argentina – Italy: n=75, Argentina – Spain: n= 245, Peru – Italy: n= 206, and Peru – Spain: n=398). Qualitative data included expert interviews (n=5 for Peru and n=7 for Argentina); and different types of semi-structured in- depth interviews targeting relatives of migrants to Spain and Italy in different household positions, including children 12 -18 years old (n=11 for Peru, and n=11 for Argentina). / text