A 3-year longitudinal study of children at risk for depression was completed, studying children (aged 8-16) of unipolar depressed, bipolar, chronically medically ill, and normal women. Nearly 100 children from 68 families were included, and the psychiatric status and functioning of the mothers and children were studied at 6-month intervals. Mothers and children were observed discussing an area of disagreement. Observations showed that unipolar women were the most negative and withdrawn; children's outcomes were specific to the communication dimension; and depressed mood was most strongly associated with withdrawal and poor task focus. Observations indicated a reciprocity of dysfunctional interactions in the family. Children's utterances showed criticism directed toward depressed mothers. Depressed mothers were specifically negative toward children with difficulties. A unique between-sibling sample of children where one was doing well and the other was not, indicated that mothers interacted differently with each. Difficulties in the quality of the mother-child relationship, and also the impact of each other's difficulties on the other, caused symptomatology. It was concluded that maternal background factors such as personal experiences in her family, current mood and stress situations, and child's own behavior, all contributed to the quality of the interaction. Further study is needed to understand maternal depressive behavior and the impact on the child. (BHK)