Published at International Proceeding of English Language Teaching Conference with ISBN: 976-602-1290-0109 Bilingualism and Sapir-Whorf Hypothesis: an Implementation of Applied Linguistics in Writing Class By: Hari Prastyo STIT Uluwiyah Mojosari Mojokerto Email: harrylinguist@yahoo.com Abstract Bilingualism relates to mastery in two languages or more. Meanwhile, Sapir Whorf hypothesis relates to linguistics relativity. According to Sapir Whorf hypothesis in linguistics relativity, language and mind have relationship. In other words, people who speak different language, they will have different thought in viewing the universe. When we combine the concept of bilingualism and Sapir Whorf Hypothesis, we will find that someone who can be master in two languages or more, he or she will have large thought in viewing the universe because of the language that he or she is master. In other words, someone who is master in two languages or more, he or she will have many ideas in viewing the worlds. This condition can help a teacher in teaching writing and also can help the students in writing process. Keywords: Bilingualism, Sapir Whorf Hypothesis, Linguistics Relativity, Writing Introduction Writing is one of some skills that must be mastered by the students when they learn certain language. English writing is an ability to write a paragraph or even an essay by using English. However, the writer will only focus on paragraph writing. In Indonesia, writing a paragraph in English is not the easy one because the students (writers) not only should understand well what they will write, but also they should be master in English. Furthermore, they should have many ideas or large point of view when they write. In order that, the result of what they write is not too narrow and easy to be understood. This paper will discuss about the contribution of linguistics theory for writing, both teaching writing and writing process. The linguistics theory that the writer will use in this paper is bilingualism and Sapir Whorf Hypothesis. Specifically, the writer will discuss about the concept of bilingualism, types of bilingualism, writing and bilingualism. In addition, the writer will also discuss about the concept of Sapir Whorf Hypothesis and the contribution of it for writing. Discussion The Concept of Bilingualism Bilingualism is the ability in mastering two languages. According to Mackey (in Chaer, 1995:112) bilingualism is a condition in which an individual uses two languages in society. However, in this paper, the writer will only focus on written language rather than spoken language. It means that the ability in using two languages will be applied in written language and in university society.