Purpose: The study explored the distinct contributions of domain-general, behavioral, and reading-specific executive function to reading comprehension, and whether reading fluency and vocabulary moderate or mediate the relations between executive function and reading comprehension. Method: Data were collected from 129 4th and 5th graders (35.66%, 28.68%, 6.98%, and 28.68% for White, Hispanic, African American, and others, respectively; 54% are girls) who completed 9 assessments of domain-general and context-specific working memory, inhibition, and switching. Additionally, children completed assessments of reading comprehension, reading fluency, and vocabulary. Results: After controlling for all variables, among executive function variables, only behavioral and reading-specific executive function independently contributed to reading comprehension. Reading fluency and vocabulary partially mediated the relations between behavioral and reading-specific executive function and reading comprehension. Reading-specific executive function appeared to be particularly important for students with weaker vocabulary. Conclusion: These findings align with the context-specific hypothesis of executive function. Context-specific executive function may be more important than domain-general executive function in reading comprehension. Reading-specific executive function may be a distinct construct representing the integration of domain-general executive function and reading knowledge. This integration can enhance the efficiency of domain-general executive function when reading knowledge is limited, playing a compensatory role in reading comprehension.