The aim is to establish a database of brain and cognitive measures monitoring neurocognitive development in healthy and clinical child groups. The applicants have gathered data from 110 children aged 8-18 yrs, including structural MR, DTI, cognitive testi ng, ERPs, hand X-ray and blood samples for measuring hormones to determine biological age. The present application is for the first follow-up of these 110 children (2009-10), increasing the sample size in this age-range to 150, and extending the age-range with 50 children from 4 to 7 yrs. In addition, effects of hormone therapy on brain will be tracked in children w/ gender identity disorder (GID). The proposal is driven by three broad hypotheses: 1) Cerebral markers of cognitive development, including mo rphometric and WM DTI characteristics, can be readily identified. These markers may precede cognitive and behavioral development and their identification will increase the understanding of normal and abnormal development. For instance, we hypothesize that attentional and executive functions will involve structural and functional brain-changes in frontal-striatal circuitry during development. 2) Cerebral markers can be used to identify children at risk for cognitively abnormal development. E.g., we have pr eviously found that smaller neuroanatomical strucures in opiate-exposed children are related to severity of attentional and behavioral difficulties. 3) Such predictors and regularities can inform diagnosis, treatment and intervention.