The overall goal of this application for an Independent Scientist Award (K02) is to support the continuing development of the candidate as an independent scientist and facilitate the candidate's interdisciplinary research progrann aimed at a better understanding the determinants and consequences of substance use disorders (SUD). Genetic influences on the liability to addiction are well documented, however, neurobiological mechanisms by which genetic factors contribute to addictive behaviors remain poorly understood. The candidate's major theoretical premise is that genetically transmitted deficits in inhibitory self- regulation of behavior constitute a core component of addiction vulnerability. The candidate's research using quantitative EEG and event-related brain potentials (ERPs) has identified a number of heritable neurophysiological indicators of behavioral regulation, however, limited spatial resolution of electrophy- siology methods impedes the identification of the underlying neural substrates. Accordingly, the candidate's first career objective is to gain expertise in functional magnetic resonance imaging (fMRI) techniques through formal coursework, hands-on training, and developing collaborative projects with neuroimaging researchers at Washington University. The second career objective is to increase the candidate's expertise in advanced methods for the analysis of genetically informative longitudinal data such as latent growth and latent class transition modeling. The research plan draws upon the candidate's ongoing studies of adolescent and young adult twins. Specific research aims are: 1) to identify neurocognitive endophenotypes for addiction and establish their commonality versus specificity and their ability to prospectively predict substance use and abuse; 2) to better characterize neural substrates of inhibitory self-regulation of behavior by adding functional neuroimaging assessments to the Pi's ongoing studies and integrating genetic, fMRI, and ERP data; 3) to provide a functional validation of genetic variants implicated in addiction vulnerability using a combination EEG, ERPs, functional MRI, neuropsychological testing, and diagnostic assessments. In the long run, establishing the links between genes, brain function, and inhibitory control of behavior will lead to a better understanding of the pathways to addiction and identify targets for prevention and treatment efforts. RELEVANCE (See instmctions): Research has documented the role of genetic factors in addictions, but very little is known about how genes exert their influence'on complex behaviors. Investigating the neurobiological pathways and cognitive processes mediating genetic influences on behavior will lead to a better understanding of the pathways to addiction and identify targets for prevention and treatment efforts.