Perhaps the most consistently replicated fact about Attention Deficit Hyperactivity Disorder is its greater prevalence among boys compared with girls. Because of the relative scarcity of girls with ADHD, most of what we known about the disorder is based on predominantly male samples. In fact, all of the field's data about the course and outcome of ADHD relies on studies of predominantly male samples. In fact, all of the field's data about the course and outcome of ADHD relies on studies of predominantly, or entirely, male samples. The sparse data that are available on girls suggests that studies of girls are warranted because there may be gender difference in the clinical expression of ADHD and, perhaps, its etiology. To help fill this gap in research, we have been conducting an NIMH-funded, family-genetic study of ADHD girls. At the completion of the current funding period, we will have ascertained 140 ADHD girls and 120 control girls along with their 264 and 402 first degree relatives, respectively. We are now proposing a five-year follow up study to assess the outcome of the girl probands and their siblings. At the follow-up assessment, we will examine the outcome of our sample in three domains of functioning: psychiatric, neuropsychological and psychosocial. Our intention is not only to determine which ADHD girls do poorly and which do well in the three domains of assessment. Our conceptual framework starts with the idea that, for ADHD children, these domains are not redundant with one another. Our multidimensional view of outcome eschews simple dichotomies such as good and poor overall outcome. Instead, we seek to determine outcome in multiple domains and to assess the validity of baseline data to predict the ranges of outcome observed at follow-up. Our main aims are to assess: 1) the persistence and remission of ADHD over a five-year neuropsychological functional and psychosocial disability and 4) the course and outcome of high risk siblings of ADHD probands. Although prior follow-up study of girls still has much to contribute regarding long-term predictors of persistence, the validity of co-morbid conditions in ADHD children, the validity of DSM-IV and the outcome of ADHD children and their siblings in multiple domains.