Purpose: We examined the extent to which achievement goals predict reading comprehension, measured by two response formats (free recall and constructed response), and how these relations differ for students with and without reading difficulties (RD). We further explored how executive functions (working memory and semantic verbal fluency) mediate the relations between achievement goals and reading comprehension. Method: We fit multigroup structural equation models with data from monolingual English-speaking fifth graders (n = 146 for RD; n = 109 for non-RD) in the United States. Results: Results revealed that achievement goals predict reading comprehension as measured by free recall but not by the constructed response format, and this pattern was moderated by RD status. For students with RD, mastery goals positively predicted performance on free recall, a relationship that was completely mediated by semantic verbal fluency, whereas performance-approach goals were negatively related to free recall. For students without RD, however, achievement goals did not predict reading comprehension as measured by either assessment format. Conclusion: Our findings underscore the need to account for motivational differences in reading comprehension and the importance of fostering mastery goals when teaching reading comprehension, particularly for students with RD.