As most Asian countries recognise English as an indispensable language for intranational and/or international communication, they are increasingly committed to strengthening and improving English language teaching (ELT). In parts of Asia where English is an official language and ELT succeeds, people may speak English among themselves. Wherever this happens, a set of indigenous language patterns develops. Similar situations have also been witnessed in countries where English is taught and learned as an international language. We need to fully understand these aspects of present-day English if we are to take advantage of English as a language for communication. One important issue is mutual communicability among speakers of different varieties of English. Based on the observation that a common language is not a uniform language, but rather a diverse language, this chapter argues that a way of dealing with English as a multicultural language for worldwide communication is not restrictive conformism but diversity management.