Groups of depressed and nondepressed mothers will be selected on the basis of self-reports of depressive symptoms and by clinical diagnostic interviews. These assessments will be repeated at 12 and 24 months to assess the course of maternal depression. The study consists of a home visit, a lab visit, and administration of questionnaires to mothers and their spouses or partners at three time points. All maternal and child behaviors during dyadic interactions will be coded as continuous streams of data for analysis of reciprocal influences within the dyad. By coding a range of behaviors such as facial affect, vocalization, physical activity, and visual attention of the mother and infant, we hope to capture variations in mother-child interactions, both between and within depressed and nondepressed dyads. Differences in styles of dyadic interactions have been shown to have important consequences on subsequent child development in several domains. In addition, experimental simulations will consist of instructed 'depressed' and 'happy' simulations of mothers with their infants. Specific simulations allow observation of changes in infant behaviors from the spontaneous episodes and comparison between depressed and nondepressed dyads.