This article investigates forms of strategic interaction between siblings during childhood. The authors argue that these interactions, characterized by notions of reciprocity, equivalence and constructions of fairness, are worked out in relation to responsibility, power, knowledge and sibling status. Birth order and age are not experienced as fixed hierarchies as they can be subverted, contested, resisted and negotiated. To explore these issues, in-depth individual and group interviews were conducted with a sample of 90 children between the ages of 5 and 17, drawn from 30 families of mixed socioeconomic backgrounds in central Scotland with three siblings within this age range. (Contains 3 notes.)