SUMMARYThis Study reviews the prevalent concepts of maturation and motivation, and develops the following points :1. Developmental and clinical child Psychology are held apart less because of à differing focus of interests than because of differing concepts of maturation and motivation.2. Maturation is à term applied in biology and Psychology to, the development of the individual by growth processes, as distinguished from development by exercise and learning. It is defined in terms of à sequence or order of phases.3. Sequences can be affected by conditioning. It is suggested that only the groundplan of life, the order of phases from birth through maturity and reproduction to death, is unalterable. Maturation is but one contributing factor, or principle, which co‐determines the more complex process of development.4. The goal‐determining factor in the individuals striving is called motivation. There are two major categories of motivation changes : (1) the basic tendency of life is to establish the individuals equilibrium. From this point of view, all changes of direction are due to environmental influences which call for adaptation to reestablish equilibrium (2). The second category, the thesis of this Study, is that life is expansion (growth and reproduction), à process involving the homeostatic mechanism. In the course of the expansive as well as of the adaptive process, the individual changes its direction. Direction changes may be experienced in the act of reproduction when the individual transmits energies to new life; again, in the act of self‐limitation when the productive energies have been exhausted; another change of direction is that from flight movements to experimentation with and mastery of stimuli.5. Three developmental theories have been forwarded. The first, based on the concept of evolution, is à structuralization theory of development. The second, à biogenic theory of development, is related to the growth process and hypothecates à parallel of physical and Psychological development. The third developmental theory describes development as à change of motivation– an adaptation process resulting from the individuals dynamic relationship to his environment.The three theories emphasize three indispensable aspects of the developmental process: organization, content and form, Dynamics and objectives.6. Only the last of these three theories explained the fact of personality immaturity in relationship to the physical maturation, since the adaptive and the physical growth process could be conceived of as relatively independent from each other.7. Objections are raised against this theory of adaptation, to the extent that it claims adaptation to be identical with development.8. Objections are raised against the definition of the discharge principle as the basic tendency of the organism and against the identification of the discharge with the homeostasis principle.9. Since homeostasis is defined as an optimal tension level, and not as its lowest possible level, there must be states of tension which are overly‐low as well as overly‐high. In states of too‐low tension, charging must be à basic tendency of the organism.10. The main properties of life are growth and reproduction– that is, expansion, in which the environment is being exploited, adapted to life, mastered by the living being. Adaptation to the environment is only à partial aspect of life, and may be used as à detour to the opposite goal.11. All living beings have à course of life during which they develop structures that anticipate future needs. Theľ work with reserves. Anľ given need of à living being must be considered as related to the present, past and future of its life. As à consequence, it is impossible to assume that à tendency related only to the moment plays à basic role in the life of the individual. The acute release tendency relates only to acute phases or features of the needs of the immediate present.12. Consequently, deferral occurs not onlt in the course of adaptation, and as an imposed phenomenon; deferral may also occur as unimposed, unlearned behavior whenever the individual is not quite prepared for à desired experience.13. Motivation during growth and during decline is described and analyzed.14. Creativity is defined as constructive activity, à process which has its biological substratum in growth and reproduction. It consists of forming new products which develop, first, from experimentation with materials, and second, from the masterful handling of those materials.15. The probability of the processes of unlearned cooperation is presented.16. Neurosis is found to originate in connection with feelings of guilt and remorse over failing oneself as well as over failing others.17. The aim of life is seen in the contribution of biologically and/or culturally constructive products which can be utilized in the buil