This study reports on the findings of a corpus-based analysis of Korean college students' use of English conjunctive adjuncts. Unlike many previous studies that mainly focused on describing the position and semantic types of conjunctions used by learners of English, this study examines grammatical errors of conjunctive adjuncts found in a leaner corpus that consists of 102,632 words written by 399 Korean college freshman students. The main findings of the study can be summarized as follows. First, learners tend to use sentence-initial coordinators even when the sentences before and after the coordinators are not long enough to warrant such usage. Second, sentence fragments occur much more frequently than run-on sentences with the 10 most frequent conjunctive adjuncts found in the corpus. Finally, learners often add unnecessary punctuation marks or omit necessary ones after conjunctive adjuncts, errors which sometimes make it difficult for readers to understand the text. All these errors amount to the conclusion that many Korean learners of English at the university level lack the necessary grammatical knowledge of English conjunctive adjuncts to use them correctlyin academic writing.