Acquiring, refining and retaining good social skills is a key challenge in human development from infancy to ageing. At the same time, the quality of our social interactions and relationships greatly impacts our physical health and well-being. We study social development to address two key questions: 1. What biological and environmental factors impact social learning and how we interact with each other? 2. Through which mechanisms do social interactions and relationships affect resilience and well-being across the lifespan? We combine research in animals with behavioural, psychophysiology and neuroimaging studies in humans to understand the impact of social interactions on individual development.