Have South Korean attitudes toward the United States deteriorated? To answer this question, RAND researchers compiled and analyzed public opinion data on those attitudes and examined selected periods in U.S.-South Korean relations to identify the sources of anti-U.S. sentiment. They found evidence of a downturn in favorable sentiment toward the U.S. but also of a more recent recovery. They recommend ways to improve South Koreans’ perceptions of the U.S. and address their long-standing grievances.