In this paper, I test the validity of two competing approaches to island effects: syntactic and functional. Based on two acceptability judgment tasks on Korean relative clauses that are closely related to double relative clauses, I argue that the functional approach is superior to the syntactic approach at least in explaining Korean data. To be more specific, the results of the experiments show that Korean relativization is mainly affected by a semantico-pragmatic constraint called the Characterization Constraint, rather than by syntactic islands, the Complex NP Constraint in particular. (Kangwon National University)