Among the topical issues of modern Russian speech therapy, a special place is occupied by the study of the problem of specific school failure (dysorphography), the study of which is objectified by an increasing number of students who are unable to fully assimilate the spelling norms of Russian writing. The problem of dysorphography is realized by speech therapists not only at the stage of school education, when the violation of the spelling norm formation process becomes obvious, but also at the stage of the formation of written speech, when we can talk about a propaedeutic approach to identifying and preventing this problem. In modern Russian speech therapy, the concept of writing is considered as a complex conscious form of speech and speech activity. The whole way of mastering speech forms in children as a practical awareness of not only the sound form of the word, but also the practical mastery of lexico-semantic and lexico-morphological representations, which are the most important prerequisites for a child’s readiness to learn spelling and grammar of writing. The purpose of this study is to identify the mechanisms of the unavailability of children with speech underdevelopment to master the basic prerequisites of orthographically literate writing and ways to prevent them.