||Kim, Jiwon, & Choe, Mun-Hong. (2019). Korean L1 speakers’ recognition and use of L2 English derivational affixes. The Linguistic Association of Korea Journal, 27(1), 1-28. The purpose of this study is to investigate Korean L1 students’ awareness of L2 English derivational affixes and the relationship between one’s morphological knowledge and overall language proficiency. A total of 150 high school students participated in the study. A diagnostic test was developed to assess their morphological knowledge with a set of high-frequency prefixes and suffixes. The results indicate that the degree of ease and difficulty in acquisition of an affixal morpheme is related to its frequency and compositionality but not with its productivity or uniformity; the acquisition of prefixes appear to differ in function of frequency while that of suffixes is more closely associated with grammatical categories. Korean students show some characteristic error patterns. Most notably, they tend to overgeneralize the prefix in- to a wide range of stems, often producing morphologically ill-formed words. A student’s ability to use suffixes predicts the student’s overall English proficiency to a significant degree, but no such relationship is found between one’s knowledge of prefixes and proficiency. Since Korean students can hardly notice and acquire L2 English derivational morphology only on the basis of natural input, explicit instructional interventions and consciousness raising seem to be necessary.