The four major papers in this volume represent a sample of current research on early development of infants and young children; they highlight the multiplicity of factors that appear to contribute to "survival" in the developmental process and in doing so offer a perspective that is at once encouraging and forbidding. It is an encouraging perspective because we are making progress in understanding; it is a forbidding perspective because we are obviously concerned here with extremely complex processes and many factors interacting with each other with the function of that interaction not presently known.