Using an experimental paradigm of on-line L2 discourse processing, this article investigated the relationship between L1 and L2 reading, and explored the possibility of the ultimate attainment of native-like L2 reading proficiency from both test-based and product-oriented perspectives and process-oriented and psychocognitive perspectives. Subjects were MA students of English majors from a major university in Shanghai. Results indicated that, with an advanced level of L2 proficiency, L2 reading is mainly determined by L2 learners’ L1 reading ability, that is, higher mental operations including predicting, analyzing, synthesizing, inferencing, and relevant background knowledge. From the process-oriented and psychocognitive perspective, an L2 reader, like an L1 reader, is constructing a coherent mental representation of what he is reading by adopting both mechanisms of suppression and enhancement. They could benefit from the networked, hierarchical structures resulting from their skilled mental structure building. Pedagogically, these findings indicated that L2 teachers need to help students develop their L2 knowledge by encouraging extensive L2 reading and gaining rich L2 reading experiences. It seems inefficient and useless to spend much classroom time training students with low-level reading skills and strategies which they have already acquired in their L1.