The idea of ​​a critical period for language acquisition, first introduced by linguist Eric Lenneberg in 1967, is a popular debate among many people. In his initial discovery of the “critical period hypothesis,” Lenneberg stated: “There are maturational constraints on when a first language can be acquired. First language acquisition relies on neuroplasticity. If language acquisition does not occur at puberty, some aspects of language can be learned but complete mastery cannot be achieved. » Lenneberg also pointed out that in the case of bilingual individuals, the critical period is divided into phases. These people must learn their first language during the first phase which ends at age seven and their second language during the second phase which ends at the start of puberty. This hypothesis has never been proven correct due to various conditions that support and refute its claim. The critical period hypothesis is based on neuroplasticity, the idea that intact parts of the brain can take over the functions of a damaged part (Harley, 2010). . However, this plasticity is mainly abundant before lateralization, during which specialization of functions occurs in both hemispheres of the cerebral cortex (Berk, 2012). While the brain is still developing, during early childhood many areas of the cerebral cortex are not yet assigned to a single function. This allows these areas to be more receptive to creating different neural pathways and learning new skills. However, as a child grows, their brain lateralizes and neuronal plasticity decreases, making it more difficult to learn skills such as communication. Although language acquisition may become more difficult to acquire as a person ages, it is not completely impossible. T...... middle of article ...... adapt to the dialect of their new environment.ReferencesTsai, L. (2003), Pervasive developmental disorders. Retrieved from http://nichcy.org/wp-content/uploads/docs/fs20.pdfWolfram, W. (1979), Speech therapy and dialectal differences. Number 3 of Dialects and educational equity. Center for Applied Linguistics. Matson, J., Wilkons, J., Smith, K., & Ancona, M. (2008). PDD-NOS symptoms in adults with intellectual disabilities: toward an empirically oriented diagnostic model. Journal of Autism and Developmental Disabilities. Retrieved from CINAHL Plus with full-text database. (Accession number 2009871850)Mugno, D., Ruta, L., D'Arrigo, VG and Mazzone, L. (2007). Alteration in the quality of life of parents of children and adolescents with pervasive developmental disorders. Health and Quality of Life Outcomes, 5 (p22-9). http://dx.doi.org/10.1186/1477-7525-5-22