The ba-construction is probably the best-known syntactic construction in Modern Standard Chinese, but little has been done on the acquisition of it by second language learners. This study fills this gap. The theoretical framework is Liu's (1997) aspectual analysis of ba. The study is experimental. The constraint on the ba-NP and the constraint on the ba-VP were investigated. The subjects were 65 students learning Chinese in the intensive Chinese program at the Defense Language Institute (DLI) in Monterey, California. They were in three proficiency groups. A group of 20 native speakers of Chinese also participated as a control group. The study involved two experiments based on video clips: production and grammaticality judgments. The subjects were asked to indicate their confidence in their judgments. Results were that even though the learners generally produced fewer ba-constructions than the native speakers, their judgments of most of the sentences were as good as those of native speakers, indicating that they had some good knowledge of the construction. Moreover, learners with similar production patterns showed different patterns in their grammaticality judgments, suggesting that the two kinds of data complement each other in our understanding of language acquisition. Results also show that the confidence dimension captured subtle differences that would not have been captured by the judgments of grammaticality alone. Production patterns used by learners to substitute for the ba-construction and error patterns have also been identified. Finally, the variation among native speakers in their judgments of the ba-construction calls for a more systematic study of exactly how native speakers of Standard Chinese use the ba-construction, especially those who have been exposed to other Chinese dialects. ISBN 3895864781. LINCOM Studies in Language Acquisition 16. 193pp. 2006.