It was hypothesized that the relation between early anxious solitude and subsequent peer relations would be moderated by early relational (maternal sensitivity) and individual factors (child school readiness). Participants were 1364 children from the National Institute of Child Health and Human Development's Study of Early Child Care and Youth Development. Anxious solitude was assessed by child care providers from 2 to 4.5 years, maternal sensitivity was observed during mother-child interactions from 2 to 4.5 years, school readiness was tested at 3 years, children's interactions with a friend were observed at 4.5 years, and friendship quantity and peer rejection were assessed by first grade teachers. Results indicate that anxious solitary children who had experienced high versus low early maternal sensitivity contributed significantly more actively to positive interaction and less actively to negative interaction with a friend at 4.5 years (these results were contingent on school readiness), and had more friends and were less rejected by peers in first grade. Although high school readiness predicted interactive competency and positive peer relationships in children low in anxious solitude, these benefits were suppressed in anxious solitary children.