This chapter is a brief overview of the respective research. Even though there is a gerat number of publications that deal in some form with feedback in the language classroom, most of these reports are about higher education and possible assessment and feedback destined to college or university students. In general, these publications are research-oriented. Above all, when the subject is language education, writing reports and seminar papers is in the foreground; only very view authors take the language classroom into account. And even then, the focus is not on second-/foreign-language learning. Therefore the overview is limited to the well-known analyses of Kluger and De Nisi in comparison to the findings of Green. On this basis, the practice-oriented models of Wiliam and Hattie and their teams are introduced and described in some detail. Even though they refer to second-/foreign-language teaching and learning to some extent, their findings are limited, because the focus is only on formative feedback.