“…Next, our results contribute to the literature on institution formation in lab experiments (e.g., Page, Putterman and Unel, 2005;Ertan, Page and Putterman, 2009;Sutter, Haigner and Kocher, 2010;Markussen, Putterman and Tyran, 2014;Kamei, Putterman and Tyran, 2015;Dickinson, Masclet and Villeval, 2015;Kamei, Putterman and Tyran, 2019;Schmidt and Ockenfels, 2021). While groups with more than four players have been studied (e.g., Rockenbach, 2006, 2014;Dannenberg, Lange and Sturm, 2014;McEvoy et al, 2011;Kamei, Putterman and Tyran, 2019), we are -to the best of our knowledge -the first to analyze group-size effects by exogenously varying the size of the group in the context of institution formation in social dilemma situations. Moreover, we do so in an environment in which the material incentives to form and the inequality in an institution of the same relative size are orthogonal to group size.…”