We develop a model that combines competitive exchange of private commodities across endogenously formed groups with public good provision and global collective decisions. There is a tension between local and global collective decisions. In particular, we show that group formation and collective...

We present a variant of a general equilibrium model with group formation to study how changes of non-consumptive benefits from group formation impact on the well-being of group members. We identify a human relations paradox: Positive externalities increase, but none of the group members gains in...