The objective of this study was to investigate separately the contribution of mother characteristics and child characteristics in dyadic interactions. This study was conducted in a unique setting, a co-operative nursery school in which each mother assumed the role of an assistant teacher once every three weeks. At the first stage, mother's family history and child's attachment were evaluated. Later on during school, mothers' and children's interactions were videotaped. The data allowed the analysis of interactions between mothers with different family histories and children from other families with different attachment types, as well as children's interactions with different mothers. Results showed a complex interplay of mother and child characteristics within an adult-child interaction. Mothers were observed to be more involved with, and to express more anger toward, insecurely attached children, especially when their own child was classified as insecure. Inspection of children's initiatives revealed that children preferred to turn to adults whose family history corresponded to the family history of their own mother. Results are discussed within the framework of attachment and family systems theories.