There is much debate in the field of linguistics regarding the distinction between code-switching and [[language transfer]].<ref name="Treffers-Daller20092">{{Citecite journalbook|last=Treffers-Daller|first=J.|editor2-first=Almeida Jacqueline|editor2-last=Toribio|editor1-first=Barbara E|editor1-last=Bullock|year=2009|titlechapter=Code-switching and transfer: An exploration of similarities and differences|url=http://centaur.reading.ac.uk/20711/1/code-switching.pdf|journaltitle=The Cambridge Handbook of Linguistic Code-switching|pages=58–74|doi=10.1017/cbo9780511576331.005|isbn=9780511576331|s2cid=58409628 |access-date=2019-07-22|archive-url=https://web.archive.org/web/20200122213609/http://centaur.reading.ac.uk/20711/1/code-switching.pdf|archive-date=2020-01-22|url-status=live}}</ref> According to Jeanine Treffers-Daller, "considering CS [code-switching] and [language] transfer as similar phenomena is helpful if one wants to create a theory that is as parsimonious as possible, and therefore it is worth attempting to aim for such a unified approach, unless there is compelling evidence that this is not possible."<ref name="Treffers-Daller20092" />
Not all linguists agree on whether they should be considered similar phenomena. In some cases, linguists refer to the benefits and disadvantages of [[language transfer]] as two separate phenomena, i.e., language transference and language interference, respectively.<ref name="Brice20152">{{Citecite journalbook|last=Brice|first=A.E.|year=2015|titlechapter=Multilingual Language Development|journaltitle=International Encyclopedia of the Social & Behavioral Sciences|volume=2|pages=57–64|doi=10.1016/B978-0-08-097086-8.23126-7|isbn=9780080970875}}</ref> In such views, these two kinds of [[language transfer]], along with code-switching, comprise what is known as cross-linguistic influence.<ref name="Brice20152" />
Part of the debate may be solved by simply clarifying some key definitions. Evidently, linguists sometimes use different terminology to refer to the same phenomenon, which can make it confusing to distinguish between two phenomena from one another in investigative discourse. For instance, psycholinguists frequently make use of the term language switching in reference to the "controlled and willed switching" to another language. However, this term is hardly used by linguists working on natural code-switching.<ref name="Treffers-Daller20092" />
