This study examined frequency-banded vocabulary performance among international students in Korean universities across NGSL Levels 1–7 and tested whether level-based change varied by national group. Eighty-seven undergraduates (Vietnam n = 50, Myanmar n = 26, Central Asia n = 11) completed a 70-item NGSL-based odd-one-out test. Descriptive statistics summarized frequency-level accuracy profiles. Item-level accuracy was then analyzed using a generalized linear mixed-effects model with fixed effects of Level, Group, and their interaction, and crossed random intercepts for participants and items. Accuracy declined as Level increased, revealing a shared zone of mid-level vulnerability, especially across Levels 3–5. The Myanmar and Central Asian groups showed partial recovery at Level 6, whereas the Vietnamese group displayed a relatively consistent downward pattern. Overall, the study shows that international students’ vocabulary performance should not be reduced to a single total score. Instead, level-based profiles reveal vulnerable ranges that can guide targeted support and groupspecific responsive input, practice, and feedback for more efficient lexical development.

1. INTRODUCTION
2. LITERATURE REVIEW
    2.1. Vocabulary Knowledge, Frequency Bands, and Lexical Profiling
    2.2. Using the NGSL as a Frequency-level Diagnostic Framework
    2.3. English Learning Contexts in Vietnam, Myanmar, and Central Asia andImplications for Vocabulary Research
3. METHODOLOGY
    3.1. Participants and Data Collection Procedures
    3.2. Instrument
    3.3. Data Analysis
    3.4. Reliability and Measurement Perspective
4. RESULTS
    4.1. Descriptive Overview of NGSL Level-based Lexical Profiles
    4.2. Overview of Group-level Performance Profiles Across NGSL Levels
    4.3. GLMM Results for Crossed Random-intercepts Logistic Model
    4.4. Item Functioning Checks Using Item Difficulty and Discrimination
5. DISCUSSION
    5.1. Summary of Key Findings by Research Question
    5.2. Performance Patterns across Groups in Sociolinguistic andEducational Contexts
    5.3. Pedagogical Implications of NGSL-based Lexical Profiling
    5.4. Limitations and Directions for Future Research
REFERENCES
APPENDIX

• Sujin Park(Visiting Professor, Minerva College, Hankuk University of Foreign Studies, Global Campus; 81 Oedae-ro, Yongin, Gyeonggi-do 17035, Korea)