Abstract: The subject of this research is the theoretical foundations of the initial stage of formation of professional competencies of the senior high schoolers. The object of this research is the educational trajectory of the senior high schoolers. The article reveals the essence of methodology on identification of correlation between the students’ choice of future profession, the desire of their parents, and teachers’ opinion. Gradual training of the teenagers regarding the ability to self-determination in the professional sphere, formation of the image of their future career are equivalent to teaching the youth to structure their life goal. The authors substantiate the importance of the early establishment of professional competencies among the high school seniors. The provided methodology in combination with the analysis of individual portfolio of a student can be used for the purpose of establishment of the further individual educational trajectory for attaining the necessary knowledge, competencies, and skills that may be required in future professional activity. The work presents the results of the formulated and tested methodology on determination of correlation between the selection of future profession by the students, opinion of their parents and teachers, as well as the methodology of identification of the leadership qualities of the students and level of socioeconomic activity. The proposed methodology allows forming the platform for the further structuring of educational trajectory of high school seniors considering their individual portfolio. The methodology has been tested in the villages of Arctic zone of Sakha Republic, where due to the socioeconomic conditions, the vector of preferences of the students can radically differ from the desires of the parents and teachers’ opinions.