This study explores Korean learners' knowledge of adverb positions in L2 English. A questionnaire of 28 items, constructed based on Ernst's (2002) scope-based theory of adverb positions, was administered to 56 Korean university students and 17 native English speakers. The data analysis revealed the following: 1) The Korean students' knowledge of adverb placement diverged from that of the native speakers in several aspects, possibly due to L1 influence or limited L2 proficiency. 2) Scope reversal errors incurred by incorrect adverb placement were relatively frequent in the learners' responses, with the low and mid proficiency groups exhibiting higher error rates. 3) The scope of manner adverbs was observed to be acquired before that of clausal adverbs, and speech act adverbs before evaluative and subject-oriented adverbs. 4) L1 influence was manifested in the avoidance of the s-final position for manner adverbs and in the interruption of the verb and object by an adverb. The status of the Interface Hypothesis in L2 acquisition (Sorace & Filiaci, 2006) was discussed in light of the results.