The article describes the developing and testing procedure of the authors' psychodiagnostic methodology aimed at studying the mechanisms of establishing the professional self-awareness of a police officer. In accordance with the goal and objectives of the research, the experiment involved 579 police officers, with 172 people being students and cadets of educational organizations of the Russian Ministry of Internal Affairs and 407 people were acting law enforcement officers of transport police administrations of the Russian Ministry of Internal Affairs (Northwestern and Ural Federal Districts). The age range of the subjects was 18-52. The ‘Limit – Experience’ inventory we developed has 5 scales reflecting essential aspects of the problem in question. The reliability coefficient for ‘life awareness’ scale is 0.82; for ‘self-realization’ scale it is 0.73, for ‘value of time’ scale it is 0.72, and for scales ‘self-determination’ and ‘general’ the coefficient is 0.69 and 0.8 respectively. The validity of this methodology has been tested by comparing its results with those of other methods for measuring similar parameters. The questionnaire can be used in operation of the psychological service of Russian internal affairs bodies, and also for further applied research in this area.