Abstract The Interaction Hypothesis is one of the explanations for second language acquisition (SLA) (Hatch 1978; Long 1983). Numerous studies have shown that interaction facilitates SLA because learners have the opportunity to negotiate language input, receive feedback and modify their output (Long 1996; Pica 2013). However, there is little experimental research on interaction from this perspective in Content and Language Integrated Learning (CLIL) settings. The main goal of this chapter is to provide an overview of the main constructs of the interactionist framework and to see how they have been researched in studies that analyze the interlanguage of CLIL learners regarding their negotiation routines, attention to form and corrective feedback episodes.