This article presents one part of a wider study which looks at the space afforded to MFL teachers to make decisions about their teaching at the planning stage and in the classroom. The article focuses on the classroom observations which were one of the sources for the collection of rich data. In an attempt to quantify the space available, the study looks for evidence of interaction between the participants in the lessons with close analysis of the work of three MFL teachers. Interaction can take on different meanings to different people and I use it to mean an exchange, not necessarily vocal, between pupils and teacher. The article looks at the space for interaction in modern foreign languages lessons and compares Key Stage 3 (KS 3) with GCSE Key Stage 4 (KS 4) classes through an analysis of the data gathered in lesson observations. For each teacher two slices of lessons are analysed allowing comparison of the types of interaction between KS 3 and KS 4 lessons. The initial findings seem to indicate that some teachers adopt a more instructional style as they move into KS 4 and closer to the GCSE examination. In GCSE classes, there is a marked increase in the number of instructions as opposed to interactions together with an indication that in KS 4, more tasks are conducted as tests than is the case in KS 3. This difference has implications for the scope available to the MFL teachers in shaping their lessons. (Contains 2 tables.)