Аннотация:The article highlights the importance of `twice exceptionality' studies and the significance of L.S. Vygotsky and A.R. Luria's ideas for this research. Twice exceptional children combine the signs of giftedness with one or several mental disabilities, specific learning difficulties, etc. In our research, we analyzed the development of writing skills in three groups of school children with different variants of mental functions development, distinguished on the basis of neuropsychological characteristics. The use of the original method of recording movements while writing, combined with a neuropsychological assessment of children allowed revealing the dependence of writing parameters and their dynamics on the strength and weakness of the components involved in the functional system of writing. According to the results obtained, each group has its own pattern of the following parameters: time, writing quality and errors, explained by the primary weakness in the child's functional system of writing and compensatory restructuring. A comparative analysis of analytical and holistic strategies use in reading was also conducted.