This chapter focuses on teachers’ interaction challenges in the Content and Language Integrated Learning (CLIL) classroom, an area which has not been extensively researched. Six content teachers from three subject areas, mathematics, biology and civics, were interviewed about their experiences of teaching their subject through a foreign/second language. The study was two-pronged, first of all taking interest in dilemmas perceived by the teachers, and, secondly, focusing on practices and strategies developed by the teachers to meet perceived challenges. Informed by second language acquisition, CLIL, and teacher cognition research, an interview guide was created, and interviews were undertaken over a two-year period. The material was coded and analysed in several stages by means of qualitative content analysis. In the analysis, two themes related to teachers’ experiences of CLIL classroom interaction dilemmas emerged: linguistic unpredictability and socio-affective barrier. In the analysis of the strategies that the teachers developed to meet the challenges, two themes emerged: translanguaging and genre. The findings resonate with results from studies of similar kind. The results of the analyses of the interviews, and how these results could inform CLIL teacher education, are presented and discussed in the final sections of the chapter.Current Issues in Second/Foreign Language Teaching and Teacher Development: Research and Practice represents a collection of selected papers from the 17th World Congress of the International Association of Applied Linguistics (AILA), which was held in August 2014 in Brisbane, Australia.Content and Language Integrated Learning in Swedish Schools (CLISS