For international environmental problems involving many countries, such as, e.g., the climate problem, it is unlikely that all countries will participate in an international environmental agreement. If some countries commit themselves to cooperate, while the remaining countries act independently and in pure self-interest, it appears to be possible to achieve a Pareto improvement if the non-signatory countries reduce their emissions, in exchange for transfers from the countries which sign an agreement. However, the paper shows that the prospect of receiving a transfer for reducing one's emissions provided the country does not commit itself to cooperation, tends to reduce the incentive a country might have to commit itself to cooperation. Moreover, if the disincentive effect of such side payments is strong, total emissions will be higher in a situation with side payments than in a situation in which the signatory countries commit themselves to not give transfers to free riding countries.