The aim of this study was to explore psychopathological and behavior impairments in Williams-Beuren syndrome (WBS) by focusing on individual differences rather than group tendencies. Parent/Guardian ratings on the Child Behavior Checklist were analyzed in order to examine the influence of gender, chronological age, and cognitive abilities on psychopathological impairment within WBS. In line with predictions, and consistent with cognitive heterogeneity in WBS, psychopathological and behavioral abnormalities were variable, with gender and specific cognitive abilities making significant and independent contributions to this variance. For gender, females were significantly more likely than males with WBS to display difficulties with externalizing problems. For specific cognitive abilities, those cognitive functions characteristic of the classic WBS cognitive profile (a strength in verbal skills and a weakness in spatial skills) related to significantly greater internalizing difficulties. Future studies should explore underlying genetic and neurological differences in individuals with WBS in order to help explain the variability in psychopathological and cognitive functions.