The effects of bilingualism on language development in children are examined. Theories suggest that bilingual children are capable of learning a second language after mastering the first. One reason is that the child has already developed the non-verbal concept of the word (because he is already using it in the primary language), so only the verbal concept needs to be built. Balanced bilinguals have been shown to be more cognitively and linguistically flexible. However, unbalanced bilinguals generally show mixed results. Introduction Impact of Bilingualism In California, bilingualism is a big problem. Most people in California are not bilingual, but there is a large minority who speak a second language. Of these second languages, Spanish is by far the most spoken, largely due to California's proximity to Mexico. Bilingualism is also a hot topic in California's political arena. The decision to stop bilingual education is a great example of this. Even though much of the population speaks a second language, such as Spanish, there are those who tout the benefits of monolingualism in schools. They cite the view that children will be confused at school and will not be able to distinguish between the two languages. Theories of Adolescent Bilingualism Cognitive Importance The purpose of this article is to explain the different effects bilingualism affects on cognitive processes, particularly language development. When we talk about how bilingualism affects language development, we are talking about cognitive implications. Bialystock and Hakuta (as cited in Seifert, Hoffnung, & Hoffnung, 1997) found that when children learn two languages ​​equally well, ... half of the paper ... f print. Developmental psychology. 33(3). 429-440. Bialystock, E., & Hakuta, K. (1994). The science and psychology of second language acquisition. In K. Seifert, R. J. Hoffnung, and M. Hoffnung, Lifespan development. Boston: Houghton Mifflin Company. Genesee, F., Nicoladis, E., & Paradis, J. (1995). Language development in the early stages of bilingual development. Journal of Child Language. 22. 611-631.Gonzalez, V. (1995). A model of cognitive, cultural, and linguistic variables that influence the concept and language development of bilingual Hispanic children. Hispanic Journal of Behavioral Sciences. 16. (4). 396-421.Pease-Alvarez, L. (1993). Moving in and out of bilingualism: Investigating home language maintenance and change in children of Mexican descent. In K. Seifert, R. J. Hoffnung, and M. Hoffnung, Lifespan development. Boston: Houghton Mifflin Company.