The authors investigated the roles of reading fluency in mediating and moderating the relation between executive functions and reading comprehension. Linguistically diverse students (n = 106) were assessed on multiple measures of reading fluency at the passage and word levels, reading comprehension, and executive functions in grade 7 and again in grade 8. Path analyses using factor scores indicated that executive functions made indirect (mediated) contributions to reading comprehension via reading fluency, controlling for oral vocabulary and processing speed in both grades. Mediation was partial, with a statistically significant direct contribution of executive functions to reading comprehension remaining. Interaction analyses indicated that executive functions also statistically significantly interacted with reading fluency in predicting reading comprehension in both grades. Contrary to theoretical predictions, these interactions were positive, with executive functions predicting reading comprehension more strongly for students with higher reading fluency. Findings indicate that executive functions are implicated in reading fluency and that the contributions of executive functions and reading fluency to reading comprehension may be multiplicative rather than additive or compensatory.