It is not surprising that there are Indonesian people who are able to communicate only in one language, i.e., their native Language (L1). Some Javanese people—the major ethnic group living in East and Central Java -are only able to communicate in Javanese; some Sundanese people—the second major ethnic group living in West Java -are able to communicate only in Sundanese; and some Banjarese—the people living in South Kalimantan province are only able to communicate in Banjarese. This is especially true for those who never experience formal education and live in villages and remote areas for almost of their lives. For those who have ever gone to and attended formal education, they are usually able to communicate at least in two different languages, i.e., their L1 and Indonesian language, their L2. Even, some Indonesian people are not only able to communicate in L1 and L2, but also are able to communicate in more languages. In relation to these phenomena, the following question is raised: “Why do some people be able to communicate only in one language while some others are able to communicate in more, different languages?”