In general, L2 learners have great difficulty mastering aspects of grammar in the second language. For example, Chinese-speaking ESL learners often fail to mark past tense in their speaking and writing (Aaronson & Ferres, 1987; Bayley, 1991; Bean & Gergen, 1990; Jia & Fuse, 2007; Krashen & Pon, 1975; Lardiere, 1998; Wei, 2000), and there are some suggestions in the literature that Chinese learners of English never master English tense (Lardiere, 1998). One question that arises is whether the failure to learn to use the past tense is due to a failure of competence or a failure of performance. If the former, then Chinese-speaking ESL learners should show such failures in all tasks including comprehension tasks.However, little research has investigated L2 comprehension of tense marking in reading. The studies (Gass, 2001; Guillelmon & Grosjean, 2001; Jiang, 2004, 2007) have showed that late L2 learners are not sensitive to certain types of grammatical marking. They have poor inflectional comprehension. It is possible that Chinese English-language learners are insensitive to grammatical violation involving tense during reading. This dissertation tests this idea.A group of English-proficient college students from Fu-Jen University in Taiwan was tested in a number of tasks. In paper-and-pencil tests, Chinese English-language learners showed knowledge of the past tense forms and the appropriate contexts for their usage. This suggests that past tense marking is learnable. Chinese English-language learners can acquire this knowledge. Does the relative mastery of past tense show up in comprehension in a similar L2 population? A reading comprehension test that measured reading time to sequential segments of a sentence indicated that unlike native speakers of English who were tested, Chinese English-language learners were insensitive to grammatical violation involving tense. This finding is consistent with the other studies, indicating that L2 learners are insensitive to grammatical marking during reading.Overall, it appears that high-functioning Chinese English-language learners can learn almost the proper way to use tense, but fail to do so during performance.