ABSTRACT
As is the case with nearly every discipline, second language acquisition (SLA) does not operate in a vacuum. There are many research areas that are related to the field of SLA. This chapter briefly touches on some of these neighboring disciplines with a focus on the multilingual learner. Although SLA is an autonomous area of research, it had its roots and initial justification in other areas, for example language teaching, and it has been strongly influenced by other disciplines, such as linguistics, psychology, sociology, and education, to name a few. The concept of bilingualism is interpreted differently in the field of SLA versus fields such as psychology and education. That is, second language researchers reserve use of the term for only those people that are truly, as shown through some linguistic measure, the equivalent of NSs of two languages.
