Objective: Academic difficulties are commonly noted in relation to ADHD. Amongst these difficulties, reading comprehension is one of the more common weaknesses observed. Within this population, weaknesses in reading comprehension may be observed even while letter and word identification present as average. Understanding the basis of this discrepancy in such cases is important when it comes to designing effective interventions. The current study sought to investigate the role working memory and processing speed played in the reading comprehension performance of children and adolescents with ADHD. Method: An archival data set was utilized for the current study. Participants (n = 136) included children and adolescents previously evaluated at an outpatient Neuropsychology clinic. The sample was 69.6% male and 30.4% female, with a mean age of 9.09 years, and a mean educational level of 4.06 years. All participants completed the WISC-IV and WJ-III-Achievement. Results: Results demonstrated significant correlations between both the Working Memory index of the WISC-IV and the Processing Speed Index of the WISC-IV with reading comprehension performance on the WJ-III-Achievement. Specifically, working memory demonstrated a moderate, significant correlation (r = .482) with reading comprehension. Similarly, processing speed was significantly correlated with reading comprehension (r = .344). Conclusion(s): Findings suggest a role of both working memory and processing speed in the reading comprehension performance of children and adolescents with ADHD. When comparing the two, a stronger relationship is observed between working memory and reading comprehension compared with processing speed. Outcomes suggest the potential utility of indirect interventions in improving reading comprehension within this clinical sample.