Maternal depression is a concurrent and longitudinal risk factor for children s development. Maternal depression exerts direct effects and indirect effects through proximal processes of mother-child dyadic interactions. Both depressed mothers and their infants are inattentive, unresponsive, affectively flat, and disengaged during naturalistic interactions, and their dyadic interactions have been described as less synchronous. Our primary objective is to investigate differences between depressed and non-depressed dyads in maternal behaviors, child behaviors, and dyadic behaviors in terms of latency, synchrony, and contingency. In the present study, we propose to examine the determinants and effects of dyadic interactions of depressed and nondepressed mothers with their infants across several domains of child development. We plan to replicate and extend previous work by observing the dyads in naturalistic as well as experimental face-to-face settings at 5, 12, and 24 months.