Background: The state of reading proficiency among children in the United States continues to be a subject of concern among psychologists, teachers, parents, policy makers, and the education community at large. Despite the widespread use of curricular methods that teach basic reading skills, there remains a large percentage of children that struggle to read. Therefore, novel approaches to reading remediation should be explored., Purpose: The aims of this study were to examine 1) the effect of a multicomponent cognitive and reading intervention on cognitive and reading skills; 2) the role of ADHD, age, sex, IQ score, and individual cognitive skills on the effectiveness of the ReadRx intervention; and 3) parent-reported behavioral outcomes following the ReadRx intervention., Methods: The current study analyzed a large real-world dataset to examine cognitive, reading, and behavioral outcomes for struggling readers (n = 3527) who had completed 24 weeks (120 hours) of intense cognitive training integrated with a structured literacy intervention using ReadRx in a one-on-one clinic setting., Results: Analyses of pretest and post-test scores showed statistically significant changes on all cognitive and reading measures including attention, visual processing, processing speed, long-term memory, working memory, reasoning, phonological awareness, Work Attack, phonetic coding, spelling, comprehension, and overall IQ score with medium to very large effect sizes. The results included an average 4.1-year gain in reading skills including a 6-year gain in phonological awareness. No differences were found based on age, sex, or ADHD status, and minimal differences were found based on pre-intervention IQ score and cognitive test scores. The study also included a qualitative thematic analysis of parent-reported behavioral outcomes revealing themes of improved cognition, academic performance, and psychosocial skills including confidence and perseverance., Conclusion: Our findings were consistent with previous controlled studies on this intervention and offer an encouraging alternative instructional approach to reading remediation that aligns with the Science of Reading and includes intensive remediation of underlying cognitive skills., Competing Interests: ALM and TMM are employees of LearningRx, the organization that created the intervention assessed in the current study. Neither have a financial interest in the organization, the intervention, or the research outcomes. ALM is also a volunteer board member of the 501c3 non-profit research institute founded by intervention’s creator. CL is a volunteer scientific advisory board member of the organization that created the intervention assessed in the current study and on the board of directors of the 501c3 non-profit research institute founded by intervention’s creator. CL receives zero financial compensation for those volunteer roles. JM is also a volunteer scientific advisory board member of the organization that created the intervention assessed in the current study. JM receives zero financial compensation for that volunteer role., (© 2023 Moore et al.)