Driven by the trend of internationalizing higher education, universities in Eastern Asia have set up an increasing number of academic programs using English as the medium of instruction (EMI). A large volume of studies on EMI contextualized in Asian countries are available. However, most of these studies focused on teachers and students’ perceptions of EMI programs, leaving two fundamental issues rarely addressed: Is university newcomers’ English proficiency ready for taking EMI courses? How efficient are existing EMI programs in preparing their students for their future careers? In this chapter, we propose the Dynamic Language Ability System (DLAS) as a framework that weaves together the modern view of language ability and dynamic Systems Thinking (ST) to resolve these two issues. Implications of the DLAS for assessing the language ability required for EMI studies, and for developing language enhancement programs are discussed.