A questionnaire study was conducted to investigate cross-cultural differences in socially appropriate behavior between Korea and Japan. A questionnaire developed by Iwata (199 1) consisted of 46 social norm statements, the degree of agreement or disagreement with which each statement was rated on a five-point scale. In the present study, another five-point scale was added to each statement to measure self-rated frequency of behavior. Questionnaires were administered to 200 Korean and 140 Japanese undergraduates during their classes. They were asked to indicate both the degree of agreement or disagreement with each social norm statement and how often they behave in accordance with the statement, on a five-point scale. Correlation coefficients were calculated between these two kinds of measures. In addition, using these coefficients, a rank order correlation coefficient was computed between the two samples. Moderate similarity was discovered in the social norms between Korean and Japanese undergraduates.