This paper introduced the science of preventive education that is applied to schools. This education is developed and implemented mainly as a universal intervention using empirical scientific data and theories to prevent health and adjustment problems for school children. Since it is an emerging cutting-edge education in schools, it includes various problems to overcome so that it could be run on a regular basis in the present school curricula. This paper attempted to comprehensively seize such problems and to suggest promising directions to overcome them. In the first part of this paper, after indicating the worsening of children’s health and adjustment problems in recent years, the basic characteristics of the science of preventive education were explained in details emphasizing the necessity of universal prevention at schools as well as treatment-like attempts. Thereafter, it was underscored to regard the fundamental causes of diseases and maladaptation as the main targets to remove in universal preventive educations. Specifically, it was suggested that such causes should be psychological ones such as distortions of personality, cognition, emotions, and behaviors. In the second part, the fundamental psychological causes leading to diseases and maladaptation were clarified focusing personality characteristics, which resulted in revealing that they are lacks of autonomy and prosociality. In doing so, we also scrutinized the developmental process of such psychological factors. In the last part, it was discussed on how this education is implemented at schools on a regular basis. Although it is difficult to implement the education at schools because of inflexible curricula, we suggested a number of crucial tactics to actualize this implementation. Finally, the collaboration of researchers and practitioners on preventive education was underscored, expecting the future status in which preventive education will be added to official classes in schools.