In this study I will compare child and adult language acquisition in Chapter 1 taking into account the factors mentioned above in order to find out how they influence the process of L2 learning and how the effects of the factors change with age. In Chapter 2, I will deal entirely with the age factor and discuss different assumptions and theories about the importance of age in both first and second language acquisition to see what impact the age has on language acquisition. In addition, I want to get answer to the question of to what extent the success of language learners is depended on their age at which they start learning an L2. Furthermore, I will intend to investigate the characteristic features of the way bilinguals acquire their two languages in Chapter 3 to compare the findings with how younger Helen Doron children ages 3-5 years, who have not acquired completely their mother tongue yet, can cope with the acquisition of Hungarian and English at the same time...