This paper attempts to discuss and categorize the types of errors made by Korean American students in an advanced Korean composition class at the University of Hawai'i in order to provide some additional criteria for distinguishing between proficient and less proficient learners of Korean. Current issues in Korean honorifics are also reviewed in order to examine the strategies learners tend to use in composition. The position taken is that proficiency can be defined in terms of both linguistic and communicative competence. It follows then that knowledge of what constitutes this competence becomes crucial, requiring some examination and criticism of existing guidelines for measuring it. Observation, analysis, and discussion of the student data lead to the tentative conclusion that interspeaker familiarity and sensitivity to pragmatic and sociolinguistic variables of Korean appear to be essential in producing smooth and natural Korean-language prose.