The goal of this research is to characterize the neurobehavioral features of fetal alcohol spectrum disorder (FASD) and attention deficit hyperactivity disorder (ADHD). Because children with these disorders often present with similar deficits in attention, memory, learning, and behavior, the extent to which they possess distinct neurobehavioral features is unclear. The proposed study will examine adolescents from the Detroit Longitudinal Alcohol cohort, whose mothers were recruited prospectively during pregnancy to over represent moderate-to-heavy levels of prenatal alcohol exposure; a high proportion of this cohort is also suspect for ADHD. Adolescents will be invited to participate in a 16- to 18-year follow-up assessment based on membership in one of the following groups: 1) FASD; 2) ADHD; 3) FASD and ADHD; and 4) neither disorder. The primary focus will be concerned with specific outcomes within the domains of executive function and arithmetic that are most likely to distinguish between these groups. Growth curve modeling will be used to examine developmental trajectories within these domains at 7.5-, 14-, and 16-18 years. This research will generate new information regarding the neurobehavioral characteristics of each disorder, thus providing new insights for educational, clinical, and pharmacological interventions. The potential health hazards associated with treating FASD with psycho stimulants in the same manner as ADHD underscore the importance for understanding distinctive features that can improve the differential diagnoses of these disorders.