Assessing giftedness is one of the inevitable processes in the identification of gifted schoolchildren which involves all the actors included in the direct contact with schoolchildren. Since the assessments are regarded as a subjective opinion of the assessor, our aim is to determine the level of certainty that we can take into account when assessing giftedness identification. In relation to that, the research is based on the validation of compliance in the giftedness assessments of schoolchildren by: teachers, parents, peers and schoolchildren's self-assessment. The research was conducted on 115 schoolchildren aged 8 and 9 in Bosnia and Herzegovina. The instruments for giftedness assessment were based on the theory of multiple intelligences. The instruments passed several validations, and their metric characteristics were determined. The content validity has been established, and it shows in a high-quality manner that the measuring instrument provides the possibility of appropriate measurement of multiple intelligences, while the reliability of the instrument is confirmed by Cronbach's alpha coefficient. The positive correlation among the perceptions of teachers, schoolchildren, peers, and the self-assessment is confirmed by Pearson's correlation analysis. The Kruskal-Wallis test, with the Dunn's post-hoc test, indicates that there is a high congruence between the assessments of all four groups of assessors. The greatest agreement in assessments was found in musical intelligence, whereas the greatest differences in assessments were detected in the combination of parents with other assessors. The findings in this research will be used for creating a software for giftedness assessment.