Objective: To investigate differences in cognitive functioning in adults diagnosed with Reading and Mathematics Disorders. Method: The sample contained 180 adults, 98 were diagnosed with Mathematics Disorder (MD), and 82 with Reading Disorder (RD), (mean age 28.8; 62.8% female; 81.1% right handed; average education 13.8 years). Groups did not differ in demographic data. Analyses were conducted on archival data from a university mental health clinic. Diagnoses were based on DSM-IV-TR criteria. Scores were obtained from measures of verbal, visual and working memory; executive functioning; visuospatial skills; verbal abilities; processing speed and attention. The groups were compared across these domains. Results: Analyses were conducted at the 0.01 level of significance. Independent samples t-tests were conducted comparing the MD and RD groups. Groups did not differ significantly on measures of memory, verbal abilities, processing speed or attention. The MD group made significantly more errors on the Category test (t(162)= 4.18; p < .001) and WCST (t(171) = 3.17; p = .001). They also performed more poorly on the Matrix Reasoning (t(135) = 4.91; p < .001) and Block Design (t(135) = 4.50; p < .001) subtests of the WAIS-III and displayed lower FSIQ scores (t(137) = 3.71; p < .001). Conclusion: The MD group displayed poorer executive functioning and perceptual reasoning abilities when compared to the RD group. This suggests that these processes contribute to difficulties with math more so than reading ability in adults. Interestingly, groups did not differ between verbal, visual or working memory, suggesting these abilities are not characteristically impaired in adults with RD and MD, as has been found in children with these disorders.