It is shown that the most important subjective-personal prerequisites of profession mastering are the individual peculiarities of psychic self-regulation of voluntary activity formed before choosing a vocation. The latter determine the typical for a person style of activity and behaviour regulation. General style phenomenon exists when individual structure and characteristic peculiarities of regulation manifest themselves in different life situations. The individual-typological differences of regulation processes are analysed, their main manifestations and connections with types of personality are shown. The level of style peculiarities accentuation and its functional specificity are considered as the basis of regulation styles' classification. It is concluded that the higher level of regulation function formation and self-regulation processes' harmonization leads to more freedom in vocation choise. When the marked regulation style exists, the importance of assistance in choise of vocation corresponding to interests and inclinations and regulatorial prerequisites as well increases.