The authors offer a unique exploration of the formative effects of children’s early life experiences, with an emphasis on interactions among neurodevelopmental, behavioural and cultural dynamics. Multidisciplinary case studies focus on specific periods of development, or windows of susceptibility, during which care giving and other cultural practices potentially have a long-lasting impact on brain and behaviour. Chapters describe in detail: how social experience interacts with neurodevelopmental disorders; how epigenetic mechanisms mediate the effects of early environment; the interaction of temperament and environmental influences; the implications of early life stress or trauma for mental health and well-being; and the cultural shaping of sexual development and gender identity. The final section translates insights from this work into a fresh appraisal of child-rearing practices, clinical interventions and global public health policy that affect the mental health and well-being of children around the world.