Formative peer assessment is an instructional method that offers many opportunities to foster students' learning with respect to both the domain of the core task and students' assessment skills. The contributions to this special issue effectively address earlier calls for more research into instructional scaffolds and the implementation of dialogic features in formative peer assessment. However, open issues remain regarding the role of assessment criteria, the benefit of formative peer assessment for transferable knowledge and skills, the role of metacognitive and cognitive processes in the provision and reception of peer feedback, and the proposed benefit of more interactive forms of formative peer assessment. Addressing the latter issue in particular, a framework of three dimensions of increasing interactivity is proposed in order to guide future research. These three dimensions comprise the learner's engagement with the core task (low interactivity), the provision and reception of peer feedback (medium interactivity), and the learner's engagement with argumentation, tutoring, and co-construction in dialogue with peers (high interactivity).