What Drives Ability Peer Effects

Abstract This paper analyzes the importance of one commonly proposed mechanism potentially driving ability peer effects in the classroom: peer-to-peer social interaction. At a large university, first-year students are randomly assigned to a year-long tutorial group and to one of two subgroups within their tutorial group. The university encourages social interaction within, and not between, these subgroups at the start of the year. Hence, each student can divide her tutorial peers into close and distant peers. We find spillovers on student performance originating from close peers only. Distant peers are unimportant. This implies that peer-to-peer social interactions drive peer effects.