This study explored the feasibility of applying the Rule Space Method (RSM) to diagnosing the strengths and weaknesses of reading ability among learners of Chinese based on their performance on the reading comprehension section of a standardized Chinese proficiency test, the C. Test. Combining literature review, instructor coding, and expert judgment, we finalized a set of eight attributes measured by 30 multiple-choice reading comprehension test items. Eight hundred and fifty seven (857) examinees took the above mentioned test, and their responses to the 30 test items were used for statistical analyses. The results showed that 90.54% of the examinees were successfully classified into one of the pre-specified attribute-mastery patterns, based on which we were able to offer detailed diagnostic reports to individual examinees regarding their mastery/non-mastery of the attributes.