This first book of a two-volume series describes current research and state of the art clinical practice the shed light on  the developmental origins of psychopathology in the first year of life, i.e. approximately up to the emergence of secondary intersubjectivity and/or walking. The second volume explores the interactional underpinnings of  psychopathology in toddlerhood, from the time of voluntarily gross motor functioning to the emergence and basic organization of symbolic language at 24-30 months.  A comprehensive approach is adopted, focusing on the fundamentally interactive nature of early development and examining interactions both with caregivers and more broadly with the socio-cultural environment. The books describe the processes involved in psychopathological trajectories and provide clinical insight into tailored, culturally sensitive therapeutic care in diverse environments.