This study examined infant response and recovery from a social challenge and parent responses. Behavioral and physiological responses were measured from forty-three 5- and 6-month-olds infants during a modified still-face procedure that used an additional still-face reunion sequence. Results confirm the hypothesis that infants of more responsive parents show more regulation than infants of less responsive parents. Infants of more responsive parents showed greater regulation of heart rate and negative affect during the final episode of the procedure than infants of less responsive parents. In addition, this procedure elicited a cortisol response (from .22 microg/dl to .31 microg/dl). Findings suggest important links between parent behavior and infant stress reactivity and regulation.