Simultaneous bilingualism

Simultaneous bilingualism is a form of bilingualism that takes place when a child becomes bilingual by learning two languages from birth. According to Annick De Houwer, in an article in The Handbook of Child Language, simultaneous bilingualism takes place in "children who are regularly addressed in two spoken languages from before the age of two and who continue to be regularly addressed in those languages up until the final stages" of language development. Both languages are acquired as first languages. This is in contrast to sequential bilingualism, in which the second language is learned not as a native language but a foreign language.

It is estimated that half of the world is functionally bilingual, and the majority of those bilinguals are 'native speakers' of their two languages. Wölck has pointed out that there are many "native bilingual communities", typically in South America, Africa, and Asia, where "monolingual norms may be unavailable or nonexistent".

Some popular misconceptions about bilingualism include the ideas that bilingual children will not reach proficiency in either language and that they will be cognitively disadvantaged by their bilingualism. Many studies in the early 20th century found evidence of a "language handicap" in simultaneously bilingual children, linking bilingualism with a lower intelligence. However, many of these studies had serious methodological flaws. For example, several studies relating bilingualism and intelligence did not account for socioeconomic differences among well-educated, upper class monolingual children and less-educated (often immigrant) bilingual children.

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