In this quasi-experimental field study, we investigated the effects of a digital support tool on knowledge about, assessment of, and feedback on self-regulated learning (SRL). Student teachers (N = 119) took the roles of learners and teachers. As learners, they wrote learning journals and received feedback on the strategies they had used. As teachers, they assessed a peer’s learning strategies elicited in the learning journals and provided feedback. A digital tool supported the participants in their role as teachers by providing additional assessment support (yes/no) and feedback support (yes/no). Assessment support was realized with rubrics, feedback support was realized with sentence starters. Our results indicated that declarative and self-reported knowledge about SRL increased in all groups. Assessment support did not foster assessment skills, but feedback support fostered the quality of the peer feedback and feedback quality in a standardized posttest. High feedback quality, in turn, predicted learners’ application of organizational (but not metacognitive) strategies. We conclude that the combination of writing learning journals and providing peer feedback on SRL is a promising approach to promote future teachers’ SRL skills. Digital tools can support writing the feedback, for example, by providing sentence starters as procedural facilitators. Such support can help teachers supply high-quality feedback on SRL, which can then help learners improve their SRL.