Content and Language Integrated Learning (CLIL) has been promoted by the European Union as a means to achieve multilingualism. While in Germany and other European countries the trend to use the L2 as a medium of instruction is increasing, in Hong Kong, however, we see a converse development. Many schools switched from English as a medium of instruction (EMI) to mother tongue education. The German CLIL concept promotes a gradual and cautious switch to L2 for only a few content subjects in the curriculum. The Hong Kong EMI approach introduces L2 after a short bridging period to most content subjects. Although the CLIL and EMI programmes both share the features of a late immersion programme, their approach to language use in classroom discourse frames is different. The current study was designed to examine the processes and effects of language learning in L2-taught content subjects. Based on samples from two history lessons in the German CLIL and the Hong Kong EMI context, classroom interaction was analysed with special focus on teacher/student talk and codeswitching. First results support the claim that constructive processes during classroom interaction are vital elements of language acquisition.