Seventy 15-month-old children were observed during 90 minutes of free play with their peers in childcare centers. The study aimed to describe individual differences in the children's contacts with peers and to explain the individual differences in relation to: (1) child temperament, (2) the quality of parental behavior toward the child and (3) the quality of the professional childcare environment. Three distinct peer contact factors emerged from our analyses; one reflects children's involvement in peer contacts initiated by peers and two reflect the positive and negative contacts initiated by the target children themselves. Children in groups with more children per caregiver were found to be involved in more contacts initiated by peers. Children with a relatively difficult temperament were less involved in contacts initiated by peers although only in cases of lower quality childcare, as assessed using the infant/toddler environment rating scale. Boys initiated significantly more negative contacts with peers than girls. In addition, more peer-directed negative initiatives were observed in lower quality childcare.