In the current study, we selected a fourth grade student with severe reading fluency difficulties to conduct a case study. We analyzed both qualitative and quantitative data to explore the theories that have been constructed during these past few decades. We found that this student had good listening comprehension and poor decoding skills at first grade. In spite of the improvement of his reading accuracy in third grade, his reading comprehension had dropped. The dissociation between his slow reading rate and decoding skills at fourth grade suggests that reading rate may have contribution to reading comprehension over and above the decoding skills. We also found that this student encountered both reading fluency and math-fact retrieval difficulties. We suspect that such deficits were related to this student's weakness of automaticity, which might attribute to his weak working memory.