Many international schools develop a formal written language policy to address language learning and use. Additionally, schools often develop a language policy as part of an authorization and or accreditation process. Although a school may have a formal written language policy, sometimes teachers are unaware the policy exists. The purpose of this study was to examine teacher knowledge of language policy in English-medium international schools in East Asia. Additionally, the researchers explored whether there were differences in teacher knowledge of language policy between schools that have an affiliation with CIS, IB, and ACS WASC and schools with no affiliation. Further, the researchers examined how often teachers followed the language policy and if the policy defined the roles of teachers. This quantitative survey-based study had 544 participants, of whom 387 were teachers. The main finding revealed that a sizeable percentage of teachers reported that their school does not have a formal written language policy or were unsure if one exists. Additional findings revealed similarities in language policy knowledge between CIS and IB schools and schools with no affiliation. Further, less than half of the teachers follow the language policy consistently, and many policies do not specify teacher roles.