This article focuses on Persian linguistics with the emphasis on grammar and word formation in the twentieth century. After presenting a brief overview of the history of the study of grammar in Iran, I discuss the recent trends in linguistics from diachronic to synchronic aspects. In Persian diachronic linguistics, we will see that most works focus on the reading, and deciphering of the old texts. In synchronic studies, there are three main stages: 1) traditional linguistics, 2) structural linguistics, and 3) generative or formal linguistics. I show how each one of these stages affects Persian linguistics in the twentieth century. Finally, I conclude the article by looking at the current state of Persian linguistics and the future prospects for the field.