In Thailand, education is the main area in which language policy is enacted, and this chapter investigates foreign language policy and practice, especially concerning English, in an attempt to shed light on language policy. We identify seven sources of English language education policy, namely, the National Education Act, national education standards, Ministry of Education recommended textbooks, isolated Ministry of Education initiatives, demand-driven changes in the types of schools, test washback, and decentralised decision making. We show that these sources present conflicting versions of language policy. To examine how the policies are implemented in practice, we interviewed principals and teachers at four representative government secondary schools. The findings show awareness of the various policies but a great diversity in how they are implemented.