The article discusses development of writing in three subgroups of schoolchildren with different profiles of neurocognitive development, distinguished on the basis of neuropsychological characteristics. Precise registration of hand movements together with neuropsychological assessment allowed establishing the dependence of characteristics of writing and their dynamics on the strengths and weaknesses of components forming the functional system of writing. It may be concluded that each subgroup of schoolchildren demonstrates a specific pattern of writing quality, timing and errors, and that this pattern emerges due to the primary weak component of a child’s functional system of writing as well as to compensatory reorganizations.