Age is an influential factor in the Second Language Acquisition (SLA). The debate on whether young learners are more successful than older learners has been going on for more than half of a century, starting from the Critical Period Hypothesis, which is based on brain structure. This study examines a range of studies revolving around the Critical Period Hypothesis in the past several decades to analyze the common SLA belief ‘Younger learners are more skillful than older learners in acquiring second language.’ The study disagrees that all younger learners are more advantageous than older learners in all areas of SLA. In fact, learners from different age categories have unique advantages and disadvantages in SLA. Moreover, the study approves a more holistic perspective on a wider range of non-biological factors that impact the success of SLA. At the end, the study puts forward a diversity of instructional methods that suit children and adolescents specifically in Vietnamese English Education context.