Reading in a second language (L2) is not a monolingual event; L2 readers have access to theirfirst language (L1) as they read, and many use it as a strategy to help comprehend an L2 text.Owing to difficulties in observing the comprehension process, little research has been conductedto determine what role the L1 plays in the reading strategies of L2 readers. Using think-aloudprotocols and retrospective interviews with 20 native speakers of Chinese and Japanese at threelevels of language proficiency studying in the United States, this study explores further thequestion of when L2 readers use their L1 cognitive resources and how this cognitive use of the L1helps them comprehend an L2 text. We conclude by suggesting that the results support asociocultural view of the L2 reading process.