According to the questionnaire held in England, in 2000s, 333 from 547 of the informers admit the usage of split infinitive constructions in casual speech only, while 108 — in standard literary language and 106 consider these constructions to be non-standard. Such discrepancy in appraisal from the author’s point of view evidently proves the fact, that linguistic norm of this phenomenon is in the process of taking up its position. The debate history on the subject has deep roots and goes back to the Old English. Today this process is still not completed. In the author’s opinion the question is revealed and actual in modern linguistics. The work is devoted to a certain research of the problem, where the author applies to the sources of appearance and development of disputes, analyzies deferent positions and puts forward her own view point.