Building Cooperation Among Groups in Conflict: An Experiment on Intersectarian Cooperation in Lebanon Han Il Chang New York University-Abu Dhabi hc665@nyu.edu Leonid Peisakhin New York University-Abu Dhabi leonid.peisakhin@nyu.edu Abstract: Societies divided along ethnic or religious lines suffer from persistent conflict and under-provision of public goods. Scholarly understanding of the means by which intergroup cooperation can be strengthened remains very limited. In this study, we set out to test the effectiveness of two interventions on intergroup cooperation: cross-group expert appeal and participation in a cross-group discussion. The laboratory-in-the-field experiment is set in Lebanon’s capital Beirut and involves interactions between 180 Shia and 180 Sunni Muslim participants. We find that the expert appeal increases intersectarian cooperation in settings that do not entail reciprocal exchange. The effect of group discussion is heterogeneous: on average, group discussion has no effect, but a deep substantive engagement with the other sect increases cooperation. Neither intervention diminishes the effectiveness of sectarian clientelistic appeals. The policy implication of our study is that intergroup cooperation can be strengthened even in regions as bitterly divided as the Middle East. Word Count: 9,864 words December 2017 We thank for helpful comments Thad Dunning, Susan Hyde, Peter van der Windt, Jeff Jensen, Rebecca Morton, Daniel Corstange, Cole Tanigawa-Lau, and seminar participants at UC-Berkeley, NYUAD, and the WESSI Alumni Workshop 2016. We are grateful to Jad Mahmoud Halabi, who provided excellent research assistance, and to Alicia Jammal at Information International, whose help with the logistics of the study was invaluable. The project was funded by an NYUAD Research Enhancement Grant. It was approved by NYUAD’s Institutional Review Board under protocol #080-2016.