The aim of this paper was to examine the knowledge of Korean students about English relative clauses in both contextualized and decontextualized situations. To this end, a study was conducted in which fifty college students of EFL participated as subjects, and data were collected by means of three methods: elicited imitation task, composition and conversation. The findings of the study indicated that subjects’ performance on comprehension and production tasks was affected by grammatical positions on which relativization occurs in relative clause. It was also shown that their performance was influenced by position of head noun in matrix clause that relative clause modifies. Based on the results of the study, two sets of ordering (i.e., the accuracy order of comprehension and the frequency order of production) in which a variety of types of relative clauses were understood and used in contextualized and decontextualized situations were offered to describe and explain the Korean learners’ performance on L2 relative clauses.