Metadiscourse is a set of linguistic ties used to communicate attitudes and denote the grammatical attributes of a text. The present study was conducted to inspect using hedging, boostering, and self-mentioning metadiscourse markers in the well-known Persian and English psychology books. Based on the chosen corpora of the study, this inquiry purposed to realize what the general preferences are in the use of hedging, boostering, and self-mentioning metadiscourse markers in Persian and English psychology books. The corpora of four psychology books, two by Persian- speaking psychologists and two by English-speaking psychologists, were chosen and analyzed based on Hyland’s (2005) model of metadiscourse. The data obtained and collected from the chosen corpora were analyzed by Ant Conc 3. 5 . 7 and SPSS statistical software. By analyzing the corpora of the study quantitatively, it is resulted that Persian-speaking psychologists used more metadiscourse markers than that of English-speaking psychologists in their books. Secondly, it is detected that Persian-speaking psychologists used fewer hedging metadiscourse markers in their books than that of their English-speaking counterparts. Thirdly, it is found that Persian-speaking psychologists used more boostering metadiscourse markers in their books than that of their English-speaking counterparts. Next, it is realized that Persian-speaking psychologists used more singular first-person self-mentioning metadiscourse markers in their books; however, their English-speaking counterparts used more plural third-person self-mentioning metadiscourse markers in their books. In addition, textual analysis has shown the difference of Persian and English sub-corpora in using hedging, boostering, and self-mentioning metadiscourse markers.
