- The interactions between premature birth and the caregiving environment on infants' cognitive and social functioning were examined. Participants were 150 infants (83 preterm, 67 full-term) and their parents. When infants were 6 months old, parents reported on their levels of emotional distress, and triadic family interactions were filmed and coded. At 12 months of age, the infants' cognitive and social functioning was assessed. Prematurity moderated the effects of maternal (but not paternal) emotional distress and triadic interactions on infants' cognitive and social outcomes. Whereas for cognitive functioning the interactions were consistent with a diathesis-stress approach, for social functioning the interactions were consistent with a differential susceptibility approach. The differential effects of the caregiving environment between groups and outcomes are discussed. © 2015 The Authors. Child Development © 2015 Society for Research in Child Development, Inc.