Vocational guidance at school can not be based on some permanent requirements of professions to a man, since the technical progress makes the professions obsolete pretty quickly. It is to be expected that future workers may have to change their field of expertise 5-6 times in a lifetime. It is not possible also to rely on stable individual-psychological qualities which are revealed by diagnostical procedures since they change significantly with age, experience, under the influence of new motives, and of life and labour conditions. Therefore more attention must be given to professional desires and intentions of the school-children. Two stages in the appearance of the latter are described; it is shown how psychological and psychophysiological procedures can successfully complement each other at these stages as means in the process of adequate vocational self-determination.