This article presents a systematic review of research related to multilingualism and multimodality in Content and Language Integrated Learning (CLIL) and English as a Medium of Instruction (EMI) classrooms. Our aim is to explore how existing research has identified the contexts and areas of study linked to these concepts. After reviewing substantial evidence on factors such as the geographical contexts, education levels, participants, languaging practices and semiotic resources employed in previous research, we introduce the articles of this special issue. These contributions cover three education stages: primary, secondary and higher education, providing an updated overview of the field. They address a range of topics related to CLIL/ EMI, including the use of multimodal resources to scaffold content and language in classrooms, the implementation of translanguaging and trans-semiotising pedagogies, teachers’ awareness of multilingualism’s pedagogical philosophies, as well as the role of multimodality in assessments, thus providing a current and holistic view of multilingualism and multimodality in the CLIL/ EMI context today.