English-Medium Instruction (EMI) helps Chinese universities recruit students from overseas and establish international student and faculty exchange programs, thereby providing additional income with less reliance on government subsidies. EMI is attractive to domestic students, simply because proficiency in English is "a passport to a host of economic, social, educational and professional opportunities and resources". EMI research traditionally draws on theoretical positions from second language or foreign language acquisition, bilingual research, systemic functional linguistics and classroom discourse studies. Professional development of EMI instructors should not focus only on improving their English, but also on enhancing their awareness of English teaching and learning and providing them with information about curriculum design, English teaching, and theories of second language acquisition. Cognitive/Academic language proficiency should be a focus for non-native English speaking instructors and students who are involved in EMI programs in China. The chapter also presents an overview of the key concepts discussed in this book.