The purposes of this study are threefold: It investigates effects of a formative assessment script (FAS) that was designed to support vocational students in generating feedback to (1) a peer’s and (2) their own performance. Effects of the FAS are investigated with respect to quantitative and qualitative characteristics of the peer and internal feedback generated by the students. Furthermore, this study examines (3) if generating peer feedback is beneficial for assessor’s generation of subsequent internal feedback. In a two-factorial quasi-experimental study, 75 vocational students firstly produced individual drafts for a typical technical planning task. Next, students either generated peer feedback (with vs. without FAS support) on a fictitious erroneous peer draft and subsequently on their own drafts or generated internal feedback only (with vs. without FAS support). Results yield beneficial effects of the FAS on generating peer feedback. Students, who were supported by the FAS-generated more comments on the peer draft, were more sensitive in detecting errors and missing information in the peer draft and generated more suggestions for improvement. With respect to assessors’ internal feedback generation, this study revealed mixed results. On the one hand, FAS-supported students generated more comments and ignored fewer erroneous elements in their own drafts. On the other hand, they neither detected more missing information nor generated more suggestions on how to improve their own drafts than students without FAS support. Unexpectedly, generating peer feedback prior to generating internal feedback had no effects on the quality of assessors’ subsequent internal feedback.