The development of the human brain through childhood is characterized by a complex interplay between anatomic, structural, cellular, chemical, and functional changes. The relationship between these physical brain changes and cognitive and behavioral aspects of development are poorly understood. Several previous studies have attempted to examine specific imaging measures (e.g., structural morphometry) as a function of age and development, but rarely is more than one brain imaging measure used for this purpose.In this study, we will perform MRI-based measurements of anatomic morphology, tissue microstructure (with diffusion-tensor MRI) and functional brain activation (with BOLD fMRI) in a population of healthy children between the ages of 10 and 12. The fMRI studies will be designed to study brain circuits of(l) emotion regulation, and (2) attention and inhibition. These measurements will be performed 3 times on an annual basis to study within subject changes in function and structure. A cross-sectional structural and functional analysis will be performed to determine if there are any developmental trends with age, gender, adolescent stage, temperament or cognitive ability. Subsequently, a longitudinal analysis will also be performed to determine structural and functional changes within single subjects. The results of this study will serve as a normative database of structural and functional brain development. Future studies of brain development in children with developmental disabilities (e.g., Autism, Fragile X, Downs, etc.) will be designed and performed based upon the results from this study.