A pertinent problem in the area of moral development is whether most people can distinguish moral from conventional issues. Some research has shown children and adolescents consider moral (intrinsic) transgressions more serious than violations of convention. To expand this research by examining in detail the role of intrinsicality in moral discriminations, and to examine Catholic students' judgments of morally and conventionally wrong sexual acts, 101 Catholic undergraduates rated the seriousness of 16 sexual and nonsexual (violations of church rules) acts. The questionnaire contained four scales to measure criteria for distinguishing between morality and convention: seriousness, unalterability, universality, and intrinsicality. The results showed that most Catholic university students saw a clear distinction between eight acts in the moral domain (intrinsically wrong), four acts in the conventional domain (not intrinsically wrong), and four acts in the prudential domain (not wrong at all). The results also revealed sex differences in the students' attitudes toward rules of their church (males saw violations of church rules as more wrong than did females) and in their attitudes toward some sexual acts (females were more emotional in their ratings of sexual acts). The results cast doubt on the validity of Kohlberg's test of moral development since the results of his test indicate that very few undergraduates can distinguish between morality and convention. (MCF)