Practical realization of some aspects of a Soviet theory of stage-by-stage formation of mental behavior for the purpose of vocational training is discussed. It is argued that practical application of the stage-by-stage procedure must be preceded by a comprehensive psychological analysis and development of a psychological model of the given kind of vocational training. Some successful and unsuccessful examples of application of the discussed methodological approach are presented. It is shown that efficient application requires multivarious research directed to optimal "coupling" of psychological requirements and of concrete (economical, manufactural, social-psychological) features of the training situation. Constructive use of achievements of the science of psychology in the practice of vocational training requires also preliminary psychological-pedagogical preparation of the training personnel.