Group externalities imply a situation where individual and group interests are not aligned and therefore require the design of rules or institutions that correct the failure in order to improve social outcomes. Public goods, team work, the use of natural resources under joint access, or any pollution problems, are examples of such potential divergence between individual and group incentives. Institutional corrections can come exogenously from a regulatory state that brings in command and control or incentive mechanisms (pecuniary or not-pecuniary), or that reassigns property rights to correct the failure. But solutions can also emerge endogenously from the group, through self-governed institutions, with similar mechanisms of material or non-material incentives, as well as social norms or conventions.
