Lexical ability, an umbrella term to cover various knowledge and skills pertaining to words in print, is a key component in reading comprehension. Little is known how different facets of lexical ability jointly contribute to L2 reading comprehension and how the contributions may differ between higher- and lower-proficiency L2 learners. This study, based on 201 adults who had studied Chinese in China, explored direct and indirect effects of distinct facets of lexical ability on L2 reading comprehension. The participants completed three paper-pencil tasks that measured three facets of lexical ability, that is, morphological awareness, character knowledge, and vocabulary knowledge. Their short-term memory, grammatical knowledge, and reading comprehension were also measured. Separate sets of path analysis showed that higher- and lower-proficiency learners had distinct patterns of relationships. Whereas higher-proficiency learners relied more on morphological awareness and vocabulary knowledge in L2 Chinese reading comprehension, lower-proficiency learners drew largely upon their character knowledge.