Research based on the CPH observation of adult some in addition to personal experience or informal observation of adult learners' difficulties has led some educators and policy makers as well as many parents to conclude that second language instruction is most likely to succeed if it begins when learners are very young. However, some studies of the second language development of older and younger learners learning in similar circumstances have shown that older learners are more efficient than younger learners. By using their metalinguistic knowledge, memory strategies, and problem-solving skills, they make the most of second or foreign language instruction. In educational settings, learners who language school level do not always achieve learning a second at primary school level do not always achieve greater proficiency in the long run than those who begin in adolescence Furthermore, there are countless anecdotes about older learners(adolescents and adults) who achieve excellence in the second language. Does this mean that there is no critical period for second language acquisition?