<p>Peer assessment can shape students' learning across cognitive, intrapersonal, and interpersonal outcomes. When students participate in peer assessment, they can take on two distinct roles, as assessors or as assessees, each of which may shape their learning differently. However, only recently, there has been interest in comparing how each role contributes to students' learning. This comparison comes with a challenge: students usually play both roles reciprocally, making it difficult to disentangle the effect of each. We conducted a scoping review to examine the methodological approaches, and the evidence generated from peer assessment studies comparing the effects of the assessor and assessee roles on cognitive, intrapersonal, and interpersonal learning outcomes. Our review identified 19 studies, most conducted in higher education contexts. They compared the differential impact on cognitive (<i>n</i> = 9), intrapersonal (<i>n</i> = 9), and interpersonal (<i>n</i> = 1) outcomes. Among the studies focusing on cognitive outcomes, a subset used designs that specifically isolated each role, yet even these produced inconsistent results: in some studies students acting as assessors outperformed assessees, while in others both roles led to similar gains. In contrast, research focusing on intrapersonal and interpersonal outcomes is largely exploratory, though it offers a useful foundation for developing more focused designs aimed at specific variables. We propose a set of guidelines for future research aimed at systematically disentangling the impact of the assessor and assessee roles on the three aforementioned outcomes.</p>