Many-sided development of human has belonged to the humanistic ideas of the philosophy since the Ancient (Classical) Ages; it is important for education and consultancy, for mental hygiene, as well as for the improvement of the labour power mobility; theoretically, from the viewpoint of the personality structure and development. Members of the Department of Psychology at the Faculty of Arts, Charles University in Prague, in cooperation with numerous graduands and graduates, have studied this problem since the sixties. From the psychological point of view, they define the many-sidedness - one-sidedness - undevelopment of the personality by means of combining data about activities, personality subsystems, motivation, and development of the individual. The one-sidedness of the personality is also expressed by means of marginal areas of the polar personality traits, while the middle zone of traits corresponds to the many-sidedness of the development The many-sided - one-sided development of activities, especially at the age of 11-19 years, was studied, too. Several forms of many-sidedness - one-sidedness - undevelopment in adolescents and grown-up persons was differentiated. From among the conditions in operation, especially the following one were studied: socio-cultural conditions of the family,important others off the family, groups and hobby-groups, common activities, way of education within the family, activity of the individual, passivity of the individual, changes in the way of life in mature age. Unfavourable conditions are, in many cases, more or less compensated by other conditions, external ones, but mainly by the individual's activity, his/her effort aimed at self-determination. The compensating, and - on the other hand - disturbing operation was expressed by means of the personality development conception in branches that diverge or converge according to the complementary conditions.
