Learner self-assessment is a significant predictor of learning outcomes (Hattie, 2018). However, it is insufficiently implemented in Czech secondaryschools (Czech School Inspectorate, 2021). One of the reasons for this may be the lack of teachers’ experience in developing their own self-assessment skills. Thispaper presents a study framed by a 12-week intervention programme to develop self-assessment skills focused on presenting in German among prospectiveteachers of German as a foreign language (n=15). The study examined the content (characteristics) of the participants’ self-assessment comments collected beforeand after the intervention program. A total of 25 self-assessment comments were collected using the “Lautes Erinnern” method (13 before the intervention, 12 afterthe intervention) and analysed using the inductive category formation of the qualitative content analysis (Mayring, 2014). The analysis revealed three maincharacteristics of the development of self-assessment: increasing evidence in the self-assessment comments, a shift in focus from the predominance of non-languagespecific to language-specific assessment, and a shift in focus from mostly negative to also positive aspects of performance. The study concludes with a discussion of the implications for better teacher education that develops their self-assessment skills appropriately.