The prerequisites of language acquisition are cognitive and pragmatic. The child's conceptual development and social needs direct his attention to particular linguistic forms. These provide an efficient selection device enabling the child to match his language learning task with his abilities. The second language learner who is cognitively and socially more advanced lacks such a natural regulator. However, because of his first language learning experience he has the lesser task of learning the language specific expressions of the language universals and not the universals per se. This may be one of the reasons that makes acceleration in second language acquisition possible. In order to be an efficient means of communication language must be clear and also expressive. The latter requirement makes it highly complex. The acquisition of the 'fine tunings' in language is a predictable, but fairly long process reaching into late adolescence. The second language learner's achievements are less predictable. He may spend less time on his language learning task. In addition, there are other factors that could account for individual differences in second language learning, e.g. acculturation, attitude and motivation, ego-permeability. (Author)