||Cheng, Yan & Lee, Borim (2020). A study of English morpheme acquisition order by Chinese and Korean EFL learners. The Linguistic Association of Korea Journal, 28(1), 79-97. The purpose of this study is to evaluate the two contrasting claims for the order of inflectional morpheme acquisition in English as L2: the natural order hypothesis and the hypothesis claiming L1 effects as a fundamental factor. This study also investigates two additional factors that may influence the acquisition of L2 English morphemes: the learners English proficiency level and the data elicitation method. For this goal, it involves 38 Korean and 38 Mandarin Chinese learners of English in college, each group of which is in turn divided into two sub-groups according to their English proficiency level. The accuracy scores for six English inflectional morphemes are obtained from two tasks, a freewriting task through journal entries and a fill-in-the-blank type test. Then the results are compared according to the various factors using Spearmans rank-order correlations based on TLU (target-like use) scores. The results of this study indicate that different L1 groups of the same proficiency level show different acquisition orders, neither of which supports the natural order hypothesis. The data elicitation method and English proficiency, however, do not seem to significantly affect the order of English morphemes. Based on these results, this study concludes that L1 plays a major role in English inflectional morpheme acquisition by EFL learners. It is also noted that input frequency and the amount of classroom instruction can be other important factors affecting English morpheme acquisition, suggesting the need to increase the inputs of low-ranked but important morphemes in the classroom.