PROJECT SUMMARY / ABSTRACT Our investigation is a developmental cognitive neuroscience examination of neural processing during early development. Brain electrical activity consists of multiple, co-occurring oscillatory rhythms that underlie functions critical to simple and complex brain processes. Spatiotemporal characteristics, functional properties, neural generators, and psychological correlates characterize these individual oscillatory rhythms in adult research. These neural signatures are essential for our understanding of brain processes involved in early self-regulatory cognitive and affective processes. Methods for examining brain systems and their oscillatory signals in infants and children, however, have long been non-systematic, lacking the level of standardization, sophistication, and scientific rigor seen in the adult research literature. There is a need for research that characterizes early brain functioning in typically developing infants and young children because it allows scientists to distinguish individual differences in development from at-risk trajectories. Our goal is to provide the first comprehensive and systematic analysis of longitudinal changes in EEG rhythms across infancy and early childhood. Our systematic examination of multiple oscillatory rhythms (delta, theta, alpha/mu, beta) will enhance understanding of their frequency signatures, spatial topographies, and functional properties, all within a developmental time course. We will address three research aims. 1) We will identify and compare developmentally appropriate techniques of characterizing neural oscillatory rhythms. 2) We will characterize ontogenetic changes in neural oscillatory rhythms and their interactions. 3) We will determine whether individual differences in neural oscillation parameters and their developmental trajectories are related to developmental outcomes.