The purpose of this research was to study the moral characteristics of late adolescents with volunteer behaviors. The samples were 150 graduate students in Chulalongkorn University, Mahidol University, and Suan Dusit Rajabhat University. The samples included two groups: 75 students with volunteer behaviors and 75 students with non-volunteer behaviors. The research instruments were the personal data questionnaire, the reasons of volunteering survey form, and the moral characteristics inventory. Discriminant Analysis with Stepwise Method analyzed data. Wilks' Lambda was used as the entry criterion. The data revealed that altruistic and devoting behaviors were able to account for 15.9 percent of the variance of group membership between late adolescents with volunteer behaviors and late adolescents with non-volunteer behaviors. In addition, the percentage of effectiveness in predicting group membership of late adolescents with volunteer behaviors and late adolescents with non-volunteer behaviors was 68.7.