Infant-sibling interactions were examined as a mechanism for understanding the development of responsive caregiving behaviors in older siblings. Twelve-month-old infants (M = 12.5 months), their 3-to 10-year-old siblings (M = 5 years), and their mothers (n = 26 infant-sibling-mother triads) were observed during separate 20minute infant-sibling and infant-mother interactions. Responsiveness to infant behaviors was analyzed using seven mutually exclusive, non-culture-specific vocal and non-vocal categories and sequential data analysis. The onset of caregiving behaviors was age-related, with siblings' responsiveness levels increasing and resembling mothers' responsiveness levels after age six. Infant-sibling interactions, non-culture-specific coding, and sequential analysis provide new techniques for examining familial interactions and the trajectory of intergenerational transmission as a function of child age and caregiver behaviors.