The papers presented in this volume, written by active and well- known researchers, discuss experimental research that has validated the importance of infancy in individual development over the age continuum. In addition, a diverse overview section contains informative chapters on conceptual models for individual differences during infancy including: individual differences from the perspective of dynamical systems theory the logic of behavioral genetic designs and their use in the delineation of genetic contributions to individual differences coverage of basic statistical treatments for individual difference data focussing on cluster analytic techniques