The purpose of this study was to reveal the effects of Westernized arrangements of traditional Korean folk music on music familiarity and preference. Two separate labs in one intact class were assigned to one of two treatment groups of either listening to traditional Korean folk songs ( n = 18) or listening to Western arrangements of the same Korean folk songs ( n = 22); a second intact class served as a control group with no listening ( n = 20). Before and after the listening treatment session, pre- and posttests were administered that included 12 music excerpts of current popular, Western classical, and traditional Korean music. Results showed that participants who listened to traditional folk songs demonstrated significant increases in both familiarity and preference ratings; however, those who listened to Westernized folk songs showed increases only in familiarity ratings but not preference ratings for the same Korean songs in traditional versions. An analysis of participants’ open-ended responses showed that affective–positive responses were used most frequently when explaining preference for traditional versions of Korean folk songs (28.1%) among the traditional Korean listening group; structural–negative reasons (47.8%) were the most frequent among the Westernized listening group.