To identify differences in neuropsychological mechanisms of spelling competence development in boys and girls, a correlation analysis of the data obtained using a complex of neuropsychological tests and the data of evaluating the written language of schoolchildren was carried out. The study group consisted of 150 children. The results of the study allow for the conclusion that the success in mastering Russian spelling in groups of boys and girls may be caused by different factors. In both groups, the correlation between the level of spelling competence and success in performance of the Kohs Block Design Test was revealed. In addition, in the group of girls, correlations were found between the success in mastering spelling skills and the state of mechanical verbal memory, as well as the development of thinking (finding the odd one out). In the group of boys, correlations were found between the number of spelling errors and signs of dynamic praxis development, copying rhythmic structures, arithmetic skills, and thinking (arranging pictures in a right sequence to make a story, listing objects belonging to the same category).