The study deals with a new aspect of training and development. By defining the validity and the competencies of the training method, the importance and the possible methodology of personality development are introduced. It is assumed that a mature personality, as a product of the individualizing process described by Jung, is a behavior-determining competency. Depending on the situation at times teaching is needed, at other times trainings, or in other cases the causes of failure related to behavior should be analyzed. If cognitive understanding is to be influenced, a teaching method should be applied, if behavioral change is aimed at, training is to be implemented, and if the causes of the behavior are to be explored other methods should be found.