Fetal Alcohol Spectrum Disorders (FASD) are associated with a broad range of neuropsychological and behavioral impairments, from diminished general intelligence to subtle attention and motor deficits. The extant literature suggests that children with prenatal alcohol exposure have mathematics difficulties, however the nature and specificity of these deficits have not been thoroughly examined. The current study sought to evaluate mechanisms of mathematics abilities in children with prenatal alcohol exposure by testing their core capacity to represent and process numerical information. Mathematics achievement and numerical processing skills in children with prenatal alcohol exposure (n = 27) and typically developing controls (n = 32) ages 8:0 to 16:11 were evaluated using the Calculation, Math Fluency, Applied Problems, and Quantitative Concepts subscales of the Woodcock Johnson III Tests of Achievement (WJ-III) and three experimental tasks designed to measure different aspects of numerical processing: approximate number sense (ANS), symbolic and nonsymbolic magnitude judgment (MJ), and automaticity of numerical magnitude processing (numerical stroop). Analysis of variance (ANOVA) techniques were utilized to examine between group differences on mathematics achievement measures and numerical processing skills. To evaluate whether performance on number processing tasks was related to global mathematics achievement in the sample, linear regression analyses were conducted with WJ- III standard scores as the dependent variable and reaction time and accuracy data from experimental tasks and group as independent variables. Group differences were observed on all four WJ-III measures of mathematics achievement, with alcohol-exposed children performing more poorly than their typically developing peers. In addition, children with prenatal alcohol exposure showed deficits on all indices of numerical processing, with the exception of MJ accuracy and numerical stroop accuracy. Overall, numerical processing abilities were positively related to children's mathematics achievement across groups, however, numerical processing abilities were also related to measures of reading and spelling. Finally, when IQ was considered in the model, differential relationships between group and IQ emerged and the relations between measures of numerical processing and mathematics achievement were attenuated, suggesting that numerical processing abilities may not represent a specific pathway underlying mathematics deficits in children with histories of heavy prenatal alcohol exposure. This investigation aids in the characterization of mathematics deficits in alcohol- exposed children. Greater understanding of the mechanisms underlying neuropsychological impairments in children with prenatal alcohol exposure will lead to more informed interventions and ultimately better outcomes for affected individuals