Adopting a cognitive perspective, this study examined roles of working memory capacity (WMC), first language (L1) syllogistic inferencing, and second language (L2) linguistic knowledge on literal and inferential understanding of L2 reading comprehension in adolescent L2 learners. Participants were 193 Korean ninth-grade learners of English. The results indicated that L2 linguistic knowledge had a paramount role in explaining literal and inferential understanding of L2 reading. Results also showed that greater WMC facilitated L2 literal reading comprehension for L2 learners with lower L2 linguistic knowledge. Better L1 syllogistic inferencing skills facilitated L2 inferential reading comprehension for L2 learners with lower WMC and lower L2 linguistic knowledge. In addition, WMC had indirect impacts on L2 reading comprehension primarily through L2 linguistic knowledge, which indicates that WMC may lead to better L2 reading comprehension, but only when learners also have greater L2 linguistic knowledge. Overall, this study suggests the different roles of cognitive resources on L2 reading comprehension depending on reader characteristics and reading subdomains and highlight the importance of examining how cognitive resources influence L2 reading comprehension.