This study explores the relationship between the time children spend outdoors with critical social and health factors. We use questionnaire data from the 2017-2018 Health Behaviour in School-aged Children (HBSC) study in Iceland, focused on children in the 6th, 8th, and 10th grades. All Icelandic schools with pupils in these classes were invited to participate. The HBSC study is based on a research collaboration dating back to 1983 and is in cooperation with the WHO Regional Office for Europe (Inchley et al., 2020). Every four years the study is conducted in more than 50 countries and regions across Europe and North America. Data is collected on children's health and well-being, social environments and health behaviours. The purpose of this paper is to better understand the social and health factors that impact children in Iceland, paying attention to the diversity of this social group, and how these factors relate to their outdoor behaviour. Our analysis focuses on children's time spent outdoors on weekdays in relation to their parents, general health, leisure, and friendship. The findings reveal a complex picture of children's outdoor lives. The results show that a great majority of children spend time outside mostly with friends and that children with poor relationships with other children spend considerably less time outside. Children's outdoor lives emerge as a social activity that strongly relates to physical and mental health. Interventions to increase time spent outside might focus on this social dimension rather than simply on the extent of outside time.