We study games played between groups of players, where a given group decides which strategy it will play through a vote by its members. When groups consist of two voting players, our games can also be interpreted as network-formation games. In experiments on Stag Hunt games, we find that that the structure of the voting rule completely determines which equilibrium is played, independently of the payoff structure. This contrasts with the play of games between individuals, where payoffs play an important role in equilibrium selection. We also explore play between groups where one member of each group dictates the play of that group. We find that the dictator tends to play a less risky strategy when choosing for a group than when playing only for him or herself. We develop a new solution concept, robust-belief equilibrium, which explains the data that we observe. We provide results showing that this solution concept has application beyond the particular games in our experiments.