Teaching English Language and Literature Society of Iran (TELLSI) Journal of new advances in English Language Teaching and Applied Linguistics 2676-2927 7 3 2025 12 01 The Role of Language in Cognitive Development from Vygotsky's Perspective: Analyzing Its Implications in Language Education 1 22 239217 10.22034/jeltal.2025.specialissue.1 EN Elaheh Negahdari Elaheh Negahdari, Master of Arts in Ancient Culture and Languages, Faculty of Humanities, Shiraz University, Shiraz, Iran Journal Article 2025 05 09 Lev Vygotsky's theory of cognitive development emphasizes the fundamental role of language in mental transformation, presenting it as the primary mediating tool for internalizing concepts, problem-solving, and behavior regulation. In this framework, language learning is not merely the acquisition of communication skills, but a cognitive and social process shaped within the context of cultural interactions. The present study aims to explain the role of language in cognitive development from Vygotsky's perspective and analyze its applications in the design of second language learning environments. This theoretical-analytical and qualitative study uses document content analysis to examine classic works and empirical research related to Vygotsky’s theory. Key concepts such as private speech, the Zone of Proximal Development (ZPD), inner speech, dynamic assessment, and language as a cultural tool have been selected as the main axes of analysis.Findings indicate that private speech plays a significant role in developing self-regulation and problem-solving abilities in language learners. Moreover, applying the concept of ZPD and scaffolded instruction in language teaching enhances learners' cognitive and linguistic skills. The analysis suggests that interactive learning environments, dynamic assessment, and the use of modern technologies—aligned with Vygotsky’s principles—can make the language learning process more effective and humane. Language is not merely a vehicle for conveying meaning but a tool for the formation of thought. Vygotsky’s theory, with its emphasis on social interaction and cultural tools, offers a comprehensive model for language education. Its practical application in instructional design can lead to the simultaneous development of language and cognition. https://www.jeltal.ir/article_239217_7c9d8f84f728dd19425e1c0471a35db5.pdf