This colloquium addresses the issue of the effectiveness of content teaching and learning through English in Hong Kong secondary schools in the context of the current moves to change the eligibility of schools to adopt English as their medium of instruction. It brings together some recent classroom-based research and development on teaching and learning through English in Hong Kong secondary schools in order to promote debate as to how this can be improved. Cummins will present an overview of the value of integrating second language and content learning. Kong and Hoare will focus on the use of English by teachers and students in the local English medium classrooms, based on data drawn from two studies on teacher explanations and student writing. Man will discuss some adaption issues of Secondary 1 English medium students switching from Chinese medium primary schools and will examine some support measures for their content learning. Walker will report on some of the difficulties students face using English for content learning in S4 and the role of an enrichment programme in supporting them. The colloquium will include an extended time for discussion on ways forward in English medium teaching and learning.