In the literature on professional self-determination there is a notion about a successful choice of a profession as conscious, independent and responsible. The analysis of errors of senior pupils when they choose a profession has shown, that the most common reason of errors is low consciousness of the main factors of the choice – «I want» and «I can». Therefore it is necessary to start the psychological support of professional self-determination of teenagers with their personal self-determination as a necessary stage of professional self-determination.