Moral thinking and moral self-concept in this research are explored by testing two groups of hypotheses concerning the differences in adolescents related to their age, gender, type of education, type of behaviour and the primary socialization group (family). The results confirm almost all hypotheses. There are no statistically significant differences found for the assumed relationship between the adolescents’ gender and the moral self-concept. The assumed connection between moral thinking and moral self-concept is confirmed. Research results show that female and male adolescents of different age, who show higher ability to identify good and bad actions and explanations, more often choose moral values as central to their moral self-concept. The observed changes in terms of both moral domains are much more obvious between early and middle adolescence in males, or between middle and late adolescence in females. Hence, the changes of moral thinking and moral self-concept are significantly affected by the factors that are associated with the processes of maturation and development. Not less important are the factors related to the type of education and the socialization process.