Little is known regarding adolescent cognitive functioning before individuals develop schizophrenia (SZ). Based on neurocognitive measures of impulsivity, we have found that nonpsychotic adolescent first-degree biological relatives of SZ patients (FDR) are more impulsive than adolescents with no SZ family history. Our study further indicates that structural and functional abnormalities in prefrontal brain regions confer increased impulsivity in FDR. These findings have led us to postulate that abnormalities in frontal-striatal interactions that mediate reward processing may underlie increased impulsivity among individuals at-risk for SZ. This ALSPAC proposal will extend our research by studying adolescent impulsivity in individuals before they are diagnosed with SZ. This project is significant because it has high potential to advance current understanding regarding SZ susceptibility. It will lead to new knowledge regarding the role of prefontal brain circuits during adolescence in mediating reward processing and impulsive behaviors prior to the clinical manifestations of SZ.