Effective management of international environmental resources requires
cooperation, and in practice cooperation is usually codified in inter
national environmental agreements (IEAs). The essential feature of IEA
s is that they cannot be enforced by a third party. This paper explore
s the properties of self-enforcing IEAs using two models. In one, the
number of signatories, the terms of the agreement, and the actions of
nonsignatories are determined jointly. In the other, the IEA is modell
ed as an infinitely repeated game, but one which is renegotiation-proo
f. Both models indicate that IEAs can do little to improve on the nonc
ooperative outcome when the number of countries that share the resourc
e is large.