Infancy and early childhood sleep-wake behaviours from current and retrospective parental reports were used to explore the relationship between sleeping arrangements and parent-child nighttime interactions at both time points. Children (N = 45) from educated, middle-class families, mostly breastfed in infancy, composed a convenience sample that was recruited from a university preschool in the Northeast US. Parents responded to the Sleep Habits Inventory, a 19-item Likert-style inventory measuring sleep-related behaviours during the last week, and the Sleeping Arrangements Questionnaire, a 30-question, open-ended, short-answer-style instrument which queries both retrospective infancy and current sleep location, bedtime routine, night waking and parent-child interactions during the sleep period. Co-sleeping in early childhood was associated with sleep location in infancy (i.e. proximity to the mother's bed) during wake-sleep transitions and night feedings. Security object use during infancy was inversely related to early childhood co-sleeping (calling for the parents, night waking, poor bedtime routine and fear of the dark). Results showed that early childhood co-sleeping in this sample was reactive, i.e. associated with current parent-seeking, night waking and social contact during wake-sleep transitions. These findings suggest that co-sleeping in early childhood is related to social experiences during infancy, particularly the amount of parent social contact and security object use. (Contains 2 tables and 1 figure.)