 This study examined the social network structure of a complete population, using data collected from administrative registers of family, household, work, school, and next-door neighbors. The researchers found that the network exhibited both scale-free and small world properties, with certain layers contributing more than others. Additionally, they suggested a new measure of excess closure, which was applied in a life course perspective to show how the social opportunity structure of individuals varied across age, socioeconomic status, and education level. This article was authored by Esther Bacani, Ilkem Heimskirk and Frank W. Takes.