With a focus on within‐person effects, this study investigated mutualism among academic skills (reading, math, science) and between those skills and verbal working memory in a general population sample and groups with high or low skills from Grades 2 to 5 (2010–2016, N = 859–9040, age 6.27–13.13 years, 49% female, ethnically diverse). Mutualism was found between reading and science in all high‐ability groups, and between reading/math and verbal working memory only in high‐math students. These results remained the same when controlled for socioeconomic status and gender, and with sensitivity analyses. High‐skill students (especially high‐math students) may improve academic performance through accumulation of academic knowledge and mutualism between academic and cognition. Such mutualism may be driven by high‐quality, intensive academic practice.