A modular approach is suggested in order to overcome shortages in the existing classifications of professions used in vocational orientation (undifferentiated criteria of fitness, inattention to dynamic aspects, etc.). The approach is based on isolation of typical structural elements in professional occupations. The latter may be represented as structures composed of a limited number of standard elements, or modules, of activity having distinct psychological characteristics. Such characteristics are compiled through analysis of psychological descriptions of professions in corresponding literature.