In this article we summarize our work on the relationships between the social environment, behaviour and stress in guinea pigs. We confirm what Jim Henry predicted to be a general rule for all mammals including man 20 years ago: The individual's degree of social stress is related to the stability of the pre- and postnatal social environment in which it lives, to the amount of social support which it receives from bonding partners and to the social experiences which it has made during behavioural development.