During recent years a new developmental science has emerged, stressing a cross-scientific perspective and the need for taking into account a broad range of factors for explaining various forms of individual development. This view is outlined by Robert Cairns (chap. 4), who with colleagues founded the Carolina Center for Developmental Science as the first center in the world with the explicit purpose of advancing developmental science. The major research paradigm for developmental science is the holistic, interactional view in which the individual is seen as an organized whole, functioning and developing as a totality. The most forceful proponent of this view is David Magnusson, who for decades has been advocating it and carrying out research in this vein at the Stockholm Laboratory for Developmental Science. His own presentation of the holistic, interactional paradigm is given in chapter 3.