Wild boar populations are strongly increasing across Europe. Although details of population dynamics and reproductive potential are known in this species, our knowledge about the social structure and a possible impact of hunting on this structure is poorly understood. Here we investigated the grouping behaviour of yearling wild boar females under enclosure housed conditions. All females were at the same age and older females (i.e., potential group leaders in a family group) were not present. The wild boar females were purchased at the age of six months from four different breeding sites. After a habituation period of (similar to)8 weeks the females were released randomly into two large enclosures, but ensuring that animals of different origin and body mass were evenly distributed. We analysed data from 111 female wild boars kept in two enclosures (enclosure east (EE): 72 females on (similar to)33 ha and enclosure west (EW): 39 females on (similar to)22 ha). Observations were carried out between March and August the year after birth (at the age of yearlings). The yearling females did not reproduce in the observation year. Data were analysed using social network analysis (SNA). We observed that the females formed stable groups during the study period. Group size did not differ significantly between the enclosures (group sizes between 16 and 20 individuals in the EE and between 11 and 17 individuals in the EW). Interestingly, the higher number of individuals lead to more instead of larger groups in the EE. Further, the group compositions were not based on the relatedness between the animals, as females from different breeding sites formed stable groups together. Rather, common habituation (familiarity) had a stronger effect on subsequent group formation. Within the groups we did not observe a linear hierarchy, although the groups were stable over time. Two females showed high betweenness values (i.e., an individual was often part of the shortest pathways in a network) compared with the average, indicating that females show differences in their connectivity within the social network of a population. Individuals with a high betweenness are very likely to rapidly spread diseases in a population and might play a key role in health management strategies.