The current study explores the patterns in which English L1, Korean L2 English and English bilingual speakers identify English /sC/ complex onset clusters perceptually in terms of accuracy rates and response times. Additionally, we testify to the predictions which markedness theory, frequency theory, and cue theory make regarding different types of /sC/ clusters: /s+Liquid/, /s+Nasal/, and /s+Stop/. We also investigate how/whether Korean L2 learners’ perceptual patterns differ from those of English bilinguals or native speakers of English. The experimental results showed a novel pattern for Korean L2 listeners such that it does not conform to any predictions by the three theories but partly seems to be consistent with input frequency or cue theory than with markedness based predictions. Also it was found that overall perceptual capacity was lower for Korean learners than for bilinguals or English native speakers, suggesting that English proficiency or input frequency mediates L2 perception. Additionally, it was found that wordhood of the stimuli, homorganicity of /sC/ clusters and individual type of /sC/ cluster affected the identification accuracy and response latencies. Thus, it is suggested that other factors might be sought to account for the variations in the perceptual patterns for complex onsets. (Daegu University)