This study evaluated the changing nature of mothers' interactive behaviors to understand alterations in children's social development across 6, 12, 24, and 40 months of age. Social skills were observed during daily activities and toy play in the home for medically high risk (HR; n = 73) and low risk (LR; n = 114) very low birthweight (VLBW) preterm and full-term (FT; n = 112) children. Variations in mothers' responses to children's changing capabilities predicted rates of change in children's social skills. For example, mothers who showed higher levels of maintaining measured across 6 to 40 months had children who displayed greater increases in initiating, but this was more apparent in daily activities than toy play and for the VLBW children compared to the FT children. Those VLBW children at the highest degrees of biological risk displayed faster gains in initiating than the other groups when their mothers provided even greater levels of support. Results demonstrate the importance of using methodologies that test more complex models of growth when evaluating parent-child relations.