The role of age in second language (L2) acquisition is a subject of much debate. The paper is to examine the role of age in L2 acquisition. In this context, the paper firstly introduces Lenneberg’s (1967) Critical period hypothesis, then further development of the hypothesis made by Johnson and Newport (1989) is offered. Following this, Felix’s (1994) Competition Model and Bley-Vroman’s (1990) Fundamental Difference Hypothesis for explaining age effect role in L2 acquisition will be presented and comparatively evaluated. Finally, a number of conclusions will be drawn with respect to the role of age effect and explanations of age role in L2 acquisition
