Abstract: Each profession, regardless of its specificity, requires a high level of professionalism from its employees. Researchers of the study propose to determine professionalism as an integral psychological characteristic of a work subject, reflecting and setting the level of a man's compliance with the occupation requirements. At that professionalism is composed of professional competence and operation success. Professional competence determines the level of main professional components knowledge and skills. The success of activity reflects the level of a meaningful goal achievement by an actor, a social recognition. The analysis of different approaches presented in the study concerning the determination of professional competence and its species suggest that professional competence being the part of a subject professionalism may also be the criterion of its development. The content and the types of professional competence are revealed on the basis of this analysis. The necessity of emotional and volitional competence identification and exploration is justified for socionomic occupations. The diagnostics of professional competence was carried out using various psychological techniques. The reliability of obtained results was provided by research and application procedure standardization concerning the modern methods of data statistical processing: correlation and factor analysis, student t-test and others. The factor analysis showed that emotional and volitional personality traits develop a single factor during the performance of professional activities by the representatives of socionomic professions. In the course of empirical research, the contents of the emotional-volitional competence is revealed for the professional activity subject, including: a strong will, self-control, flexibility, determination, self-sufficiency, attentiveness, patience, emotional stability, neuro-mental stability, self-motivation, the integrative level of emotional intelligence, programming, the overall level of self-regulation. The diagnosis of emotional and volitional competence allows to optimize the psychological support of activities for the socionomic profession representatives at the stage of adaptation and during their whole professional activities to perform the quality diagnosis of employees which will increase the level of professionalism.