ABSTRACT Introduction: Reading disability (RD) and Attention Deficit Hyperactivity Disorder (ADHD) symptoms often co-occur in school-age children. Methods: The present study evaluated the performance of 216 Brazilian children from 3rd and 4th grades on “cool” executive function (EF) abilities and phonological processing. The children were divided into three groups: those with ADHD symptoms only, those with RD only, and controls. Results: MANOVA analyses, controlling for age and nonverbal intelligence, showed worse performance for the RD group, compared to the ADHD symptoms group, on measures of phonological processing (phonemic awareness, phonological short-term memory, and lexical access) and “cool” EF components (orthographic verbal fluency and processing speed). The ADHD symptoms group did not differ from the control group on the majority of the “cool” EF tasks. Compared to the control group, the ADHD symptoms group and the RD group both showed significantly more errors in rapid automatized naming of figures, which evaluates the inhibition component of EF; performance on this task was similar for these groups. Conclusion: We conclude that children with RD have greater impairment in phonological processing and “cool” EF compared to those with ADHD symptoms. Furthermore, deficits in inhibitory control may be shared among children with both conditions.