This interdisciplinary course focuses on the structural development of the Persian language from Old Persian (551 BC) to Modern Persian (7th century) with the emphasis on the word formation and grammar. The course consists of two main parts: The first part focuses on an overview of the Old Persian and Middle Persian languages, their linguistic features and writing system and the factors that changed Old Persian to Middle and then Modern Persian. The second part of the course concentrates on the structural analysis of Iranian languages including Dari, Tajiki, Balochi, Kurdish, Pashto …. The lecture is based on texts and articles written by theoretical linguists, historians, sociolinguists, descriptive, and historical linguists. This course also examines the role of language in maintaining cultural identity and shows the type and the mechanism of the development of Iranian languages in general and of Persian in particular.