This paper explores the linguistic and interactional properties of computer-mediated communication in Taiwan. It collected data from messages posted asynchronously on Internet websites. The three primary sources of messages were, in volume order, online Bulletin Board Systems (BBSs), chatrooms, and MSN messenger. The paper identifies innovative uses of English and Mandarin Chinese hybrids, examines their function, and explores the online interlocutors’ ideologies when using them. Because of computer hardware and software, English plays an essential role even in a Mandarin-dominant online discourse by offering English expressions, words, pronunciations, and Roman letters to give loanwords, euphemisms, abbreviations, sentence-final particles, and emoticons in unique ways. The resultant hybrid language forms are easier to type, playful, funny, friendly, and trendy. The writer’s personality and cultural mentality are disclosed in such communication. Many speakers are alarmed about the effects of this language practice — the online interaction between English and Mandarin Chinese — on the development of Chinese in Taiwan.