This study examined contributions of lexical factors to native-speaking raters’ assessments of comprehensibility (ease of understanding) of second language (L2) speech. Extemporaneous oral narratives elicited from 40 French speakers of L2 English were transcribed and evaluated for comprehensibility by 10 raters. Subsequently, the samples were analyzed for 12 lexical variables targeting diverse domains of lexical usage (appropriateness, fluency, variation, sophistication, abstractness, and sense relations). For beginner-to-intermediate speakers, comprehensibility was related to basic uses of L2 vocabulary (fluent and accurate use of concrete words). For intermediate-to-advanced speakers, comprehensibility was linked to sophisticated uses of L2 lexis (morphologically accurate use of complex, less familiar, polysemous words). These findings, which highlight complex associations between lexical variables and L2 comprehensibility, suggest that improving comprehensibility requires attention to multiple lexical domains of L2 performance.