The article argues for the urgency of research on an individual’s intellectual and creativegiftedness and emphasizes the theoretical, psychological, pedagogic, and socio-economicsignificance of the problem. It is claimed that the psychological practices in education may result innegative consequences through lack of high validity methods of diagnosing mental (intellectualand creative) giftedness. The selection of relevant psychodiagnostic procedures and methods ofworking with gifted individuals must be determined by a psychologically substantiated systemictheory of giftedness which is based on contemporary ideas of uniqueness and originality of theabove-mentioned integral phenomena of the human psyche.The author provides a critical analysis of the psychometric (testometric) approach to diagnosingintellectual and creative giftedness (IQ index and creativity index). It is claimed that standardizedtests are a priori unfit to objectively measure either the actual or the potential mental giftedness ofan individual.The article explores the classifications of giftedness types in terms of quantitative criteria(indices), personality traits, occupations, motivation. The author questions the correctness ofpositing ‘creativity’ as an independent type of giftedness. It is argued that mental (intellectual andcreative) giftedness is an inseparable structural and functional unity, a systemic attribute of psycheand is revealed as talents, personality traits and metacognitive experience in various activities.The author argues for the cognitive style approach to diagnosing mental giftedness. It ishypothesized that it can serve as a theoretical foundation for developing a systemic technique ofdiagnosing general giftedness, complies with the main principles of humanizing the educationalspace in Ukraine and is truly child-oriented, i.e. considers every individual’s uniqueness andinimitability.