The problem of staff efficiency is considered within the framework of the methodology of the system research methodology, the development principle and the activity approach. Psychological principles of the study of mechanisms of professional efficiency improving are identified. The original method of research, development and assessment of psychological mechanisms of regulation of professional efficiency is presented. The following aspects are covered: dynamic personal development in the course of everyday human activity and at work, personal improvement and self-education control of professional activities and behavior with regard to specificity of changes in an organization as well as building up a balanced system of their correlation identification of basic psychological mechanisms of self-regulation of professional activities.