RT Journal Article SR Electronic T1 How Do Peers Impact Learning? An Experimental Investigation of Peer-to-Peer Teaching and Ability Tracking JF Journal of Human Resources JO J Hum Resour FD University of Wisconsin Press SP 0918-9770R2 DO 10.3368/jhr.57.1.0918-9770R2 A1 Erik O. Kimbrough A1 Andrew D. McGee A1 Hitoshi Shigeoka YR 2020 UL http://jhr.uwpress.org/content/early/2020/01/08/jhr.57.1.0918-9770R2.abstract AB Classroom peers presumably influence learning by teaching each other. Unfortunately, little is known about peer-to-peer teaching because it is never observed in field studies. The efficacy of this teaching likely depends on the ability of one’s peers. We investigate the mechanisms of peer effects experimentally to establish the importance of peer-to-peer teaching and how it is affected by ability tracking—grouping students of similar ability. While peer-to-peer teaching improves learning among low-ability subjects, the positive effects are offset by tracking. Tracking reduces peer-to-peer teaching, suggesting that low-ability subjects suffer from the absence of high-ability peers to teach them.