This paper looked into the relationship between the age factor and the development of bilinguality and second language learning. In the process, the following conclusions were reached. First, the avaliable evidence does not consistently support the hypothesis that younger second language learners are globally more efficient and successful than older learners. Second, nor is it possible from the evidence that older second language learners are globally more efficient and successful than younger learners. Third, with regard to the notion that different age-group excel in different aspects of second language learning the evidence does not consistently support the hypothesis that younger learners are inevitably more efficient than older learners in the phonetic and phonological domain. Fourth, concerning the hypothesis that those who begin learning a second language in childhood in the long run generally achieve higher levels of proficiency than those who begin later in life, there is some good supportive evidence and no actual counter-evidence. Finally, the available evidence only minimally supports the idea that there are age-related differences in the process of language.