Teachers' efforts to manage classroom social dynamics can have positive effects on students' social relationships. One way that teachers may seek to manage these relationships is through seating arrangements. In a randomized control trial, van den Berg, Segers, and Cillessen (2012) found that closer proximity in the classroom can reduce disliking between two students who dislike each other (target students). However, the effect of this intervention on the larger class is unknown. The present study implemented a short version of this seating chart intervention, investigated effects on both target and non-target students, and explored whether teachers' efficacy to manage social dynamics moderated the effects of the intervention. Data came from 1573 students in 59 Grade 5 classrooms in the Netherlands. Results indicated that students in intervention classes exhibited more overt aggression, and perceived less cooperation among classmates than students in the control condition. These effects were consistent across target and non-target students, and were not moderated by teachers' efficacy for managing social dynamics. It may be that the intervention initially causes tension between target students that is resolved first at the dyad level, and is only later noticed by other classmates. Whether these initial negative effects for target and non-target students become positive after a longer period of adjustment and reorganization of relationships is to be determined in further research. [This paper was published in "Journal of Experimental Child Psychology" v191 Article 104742 2020.]