This study investigates the relationship between L2 proficiency and different types of glosses. Just under 330 university students in Korea were divided into higher and lower levels of English fluency, and were further divided into four gloss conditions (no-gloss, L1 gloss, L2 gloss, and L1+L2 gloss). They read passages, completed an immediate vocabulary test and a survey, and took a delayed vocabulary test after four weeks. According to the findings, the L1 gloss and the L1+L2 gloss were effective for lowerlevel learners, and the L2 gloss and the L1+L2 gloss were effective for higher-level learners. However, on the survey, the L1+L2 gloss type was the most preferred gloss type of the participants. Considering the statistical analysis of the interaction effect between L2 proficiency and gloss type together with the results of the student opinion survey, L1+L2 glosses are likely the best gloss type for reading materials at any proficiency level.