Among the many factors that affect second language learning and teaching practices, age has been always considered an important factor. The beginning age for learning a foreign language is a controversial issue concerning which various ideas have been proposed by different scholars. Some researchers refer to the concept of critical period hypothesis for L1 acquisition and claim that before puberty is the best time to start teaching a second language. On the other hand, some other researchers reject the application of this hypothesis in second language learning relying on the evidence that adult learners can acquire a second language more easily at least in some aspects of language. In their claims, these researchers refer to the concepts like multiple critical period and the presence of motivation based on which any person can begin learning a second language at any age. The findings of the current paper are of important implications for the field of foreign/second language teaching.