ABSTRACT
This chapter explores the following explanations for differential success: language aptitude, social-psychological factors, personality, cognitive style, hemisphere specialization, learning strategies, and a few others. One of the major conundrums in the SLA field is the question of differential success. While it is surely the case that some people are more dextrous than others in using their mother tongue, all children with normal faculties and given normal circumstances master their mother tongue. Furthermore, there is a much broader range of language proficiency achieved among second language learners than first. One of the most obvious potential explanations for the comparative lack of success of second language learners is that SL learners begin acquiring the language at a later age than do first language learners. There is, however, a host of other factors which have been proffered to explain differential success among SL learners, to explain why some acquire a SL with facility while others struggle and only meet with limited success.
