The previous volume in this series (Blass, 1986) focused on the interface between developmental psychobiology and developmental neurobiology. The volume emphasized that an understanding of central nervous system development and function can be obtained only with reference to the behaviors that it manages, and it emphasized how those behaviors, in tum, shape central development. The present volume explores another natural interface of developmental psy chobiology; behavioral ecology. It documents the progress made by developmental psychobiologists since the mid-1970s in identifying capacities of learning and con ditioning in birds and mammals during the very moments following birth-indeed, during the antenatal period. These breakthroughs in a field that had previously lain dormant reflect the need to "meet the infant where it is" in order for behavior to emerge. Accordingly, studies have been conducted at nest temperature; infants have been rewarded by opportunities to huddle, suckle, or obtain milk, behaviors that are normally engaged in the nest. In addition, there was rejection of the exces sive deprivation, extreme handling, and traumatic manipulation studies of the 1950s and 1960s that yielded information on how animals could respond to trauma but did not reveal mechanisms of normal development. In their place has arisen a series of analyses of how naturally occurring stimuli and situations gain control over behavior and how specifiable experiences impose limitations on subsequent development. Constraints were identified on the range of interactions that remained available to developing animals as a result of particular events.