Language attrition, i.e. "the non-pathological decrease in a language that [has] previously been acquired” (Köpke & Schmid 2004: 5), is still a relatively new field of research. So far, it has mainly been investigated with regard to the L1 that is lost in an L2 environment or the L2 that gets lost in an L1 environment. The research project which is at the centre of this thesis examines L2 and L3 attrition in an L3 and an L2 environment respectively as well as metalinguistic awareness after an attrition period of four months. The outcomes have significant implications for language learning (in the educational context).