Social dimensions of the caregiving environment, like secure relationships to caregivers and high interactional classroom quality, are seen to directly or indirectly stimulate children's learning and development. However, little is known about the underlying processes, specifically with regard to the role of peers. To fill this gap we videotaped 130 children (12-36 months, 56 female) in 35 German childcare centres during morning free play and collected data on the amount of social participation with caregivers and peers as well as on individual child characteristics, attachment status and global interaction quality. These informations were used to predict learning related behaviour during the observation period. We found high interindividual variance in social participation and the activation of learning potential in play and exploratory behaviour. Both global interaction quality and direct participation in social interaction with caregivers and peers proved to be relevant for learning related behaviour.