To gain a deeper understanding of English-as-a-foreign-language (EFL) teachers’ knowledge, thoughts, and beliefs about written feedback (WF), this thesis explored four Swedish upper secondary school EFL teachers’ cognitions about WF, the sources of their cognitions about WF, and ways in which their cognitions about WF are reflected in their actual feedback practices. To carry out this exploratory investigation, the study made use of semi-structured interviews, sample student texts with teacher WF, and stimulated recall interviews. Using thematic analysis, the findings revealed five main themes of cognitions about WF: WF as a tool based on student needs, basis for discussion, precise error, progression tracker, and self-sufficiency. The findings also show that the three main sources of cognitions about WF were receiving WF, practicum & teacher education, and learning by doing. An implication of this study is that EFL teachers need to give different types of WF depending on the learner.