Purpose: Multiple preterm birth is associated with more maternal psychological distress and less positive mother-infant interactions than singleton preterm birth. This study's purpose was to compare psychological distress and the relationship with their infants in mothers of multiples and mothers of singletons. Design: An exploratory secondary analysis of longitudinal data. Sample: 236 mothers and their preterm infants. Main outcome variables: Maternal psychological distress (depressive symptoms, anxiety, posttraumatic stress [PTS], parenting stress), the mother-infant relationship (worry; child vulnerability; maternal positive involvement and developmental stimulation; and child developmental maturity, irritability, and social behaviors), and the home environment. Results: Mothers of multiples had greater PTS symptoms at baseline, anxiety at discharge, and depressive symptoms at six months than mothers of singletons. Mothers of multiples also had more positive home environments at six months. Multiple birth was a risk factor for psychological distress but not for less positive mother-infant interactions.