Nothing has emerged with more force from infant observation than the finding that the baby is oriented to the object in reality, i.e., to interpersonal reality. At the center of this paradigm shift in our understanding of mental development is the work of Daniel Stern. Scarcely less dramatic is the contribution of Edward Tronick, whose work with the “still face” has transformed our understanding of the infant's shared consciousness with the caregiver.

We have just begun to work out the signif icance of these new understandings of infant mental development for later mental development, cognitive psychology, the theory of mind, and the technique of the psychotherapies, including psychoanalysis. Although the Boston Change Process Study Group (BCPSG) invoke dynamical systems theory,1 the power of their paper comes from these new