![enter image description here][1] **Description of the Project** Feedback plays an essential role in the professional development of trainee teachers during their practical training. The content of this feedback is still largely unexplored. This paper explores what criteria teacher trainers use as a basis for the feedback they give to trainee teachers. 127 teacher trainers (52 % female, average age: 52.3 years) from 10 of the 16 German federal states took part in the cross-sectional online survey. The frequency of feedback criteria as well as subjective beliefs about teaching quality and attitudes towards scientific theories were obtained on the basis of self-reports. The findings indicate that feedback from teacher trainers focuses on the deep structures of instructional quality. Dismissal of scientific theories partly influences how often which characteristics of instructional quality are addressed in feedback. Gender, age and professional experience of teacher trainers have little influence on the content of the feedback they give. **Dataset:** https://osf.io/4ytpn/ **Codebook:** https://osf.io/usmb4/ **Talks / Presentations:** Wisniewski, Benedikt; Siegel, Stefan T. (2020, Dezember): Professioneller durch Feedback? Ergebnisse einer explorativen Studie zu Feedback in der zweiten Phase der Lehrerbildung. Koreferat beim 5. Symposium »Lehrkräfteprofessionalität« des Projekts (LeHet) an der Universität Augsburg, Augsburg. [https://osf.io/yrw2f/][2] Siegel, Stefan T.; Wisniewski, Benedikt (2021, August): What is Really Important? Results of a Study on Feedback in the Second Phase of Teacher Training. Vortrag bei der 19. Biennial EARLI Conference 2021 “Education and Citizenship: Learning and Instruction and the Shaping of Futures” in Göteborg, Schweden. [https://www.earli.org/EARLI2021][3] **Publication:** Wisniewski, Benedikt & Siegel, Stefan T. (2020): "Worauf kommt es wirklich an? Eine explorative Studie zu Feedback in der zweiten Phase der Lehrerbildung [What is Really Important? – An Explorative Study on Feedback in the Second Phase of Teacher Training]" In: *Lehrerbildung auf dem Prüfstand [Teacher Education under Review]* 13 (2), S. 240–260, [https://www.vep-landau.de/produkt/lehrerbildung-auf-dem-pruefstand-2020-13-2-kap-5-digital/][4] ![enter image description here][5] [1]: https://files.osf.io/v1/resources/yrw2f/providers/osfstorage/603c0d2967386c024b61ca8a?mode=render [2]: https://osf.io/yrw2f/ [3]: https://www.earli.org/EARLI2021 [4]: https://www.vep-landau.de/produkt/lehrerbildung-auf-dem-pruefstand-2020-13-2-kap-5-digital/ [5]: https://files.osf.io/v1/resources/yrw2f/providers/osfstorage/6127f29038595800912ef97f?mode=render