ABSTRACT
The field of Second Language Acquisition (SLA) is a branch of applied linguistics that has a history extending over half a century. It investigates the human capacity to learn additional languages during late childhood, adolescence, or adulthood, once the first language, in the case of monolinguals, or the first languages, in the case of bilinguals and multilinguals, have been acquired. SLA researchers strive to shed light on four overarching questions:
1 How do humans learn additional languages after they have learned their first? 2 In what ways is the learning of an additional language different from the learning of
languages for which exposure is available from birth, and in what ways might it be similar? 3 What factors contribute to the variability observed in rates and outcomes of additional
language learning? 4 What does it take to attain advanced language and literacy competencies in a language
that is learned later in life?
