Understanding the relationship between lexical coverage (i.e., the number of words known in a text) and second language (L2) reading comprehension is pivotal to L2 instruction as it helps teachers set sensible vocabulary learning goals and select suitable reading materials. This study examined the unique contribution of 7 lexical coverage figures (i.e., 90%, 95%, 96%, 97%, 98%, 99%, and 100%) to the comprehension of narrative and expository texts read by Chinese EFL undergraduate students (N = 234). Participants completed the Vocabulary Size Test, a L2 reading ability test, a background knowledge test, reading comprehension tests, and topic familiarity ratings. Results of hierarchical regression analyses showed that after accounting for L2 vocabulary size and L2 reading ability, lexical coverage remained a steady, though weak, predictor of narrative and expository comprehension scores. No indication of a lexical threshold for reading comprehension was found. Instead, lexical coverage was found to be a stronger predictor of expository comprehension scores than narrative. While findings suggested 98% lexical coverage was reasonable for satisfactory comprehension of L2 narrative texts, 100% lexical coverage may be needed for satisfactory comprehension of L2 expository texts without the support of background knowledge. Pedagogical implications were discussed in relation to the findings.