Using Swedish register data, we analyse how life course preferences and sibling ties are related to the geographical dispersion of siblings. We argue that life course preferences and sibling ties are influenced by siblings' sociodemographic characteristics, by similarities and differences between them, and by their family background. The measurement of geographical dispersion, the nearest neighbour index, allows us to go beyond dyadic relationships and investigate entire networks. Results from the OLS regression analysis show that life course preferences are related to the dispersion of siblings and that differences between siblings are associated with a greater geographical dispersion than similarities are. Sibling ties developed during childhood also seem to be associated with the dispersion of sibling networks. Copyright © 2012 John Wiley & Sons, Ltd.