The classical version of early development by psychoanalysis has been largely challenged by developmental psychology, and particularly by attachment theory. Psychopathology appears to be much more linked with a sequence of events involving interpersonal relationship disorders rather than with intra psychic conflicts, as hypothesized by drive theory. Establishing synchrony between parent and infant is probably one of the major tasks of the first year of life. Attachment theory appears to be the modern paradigm to understand how the several types of answers from caregivers to stressing situations in the infant give way to different emotional and cognitive regulatory strategies, with impact on the effectiveness of the stress buffer systems. This paper presents what we can figure out about what is time to the infant, the importance of synchronization within infant and caregiver, the key concept of attachment disorganization, the concept of sustained social withdrawal as a defense mechanism and an alarm signal when synchronization fails, and finally the key issue of conditions for effectiveness of early parent- infant preventive intervention.