Beside the classic example of the lighthouse, economists present military expenditures as the epitome of the useful domestic collective good. Nevertheless, overall world military spending may also be presented as an undesirable international public good, contrary to international security and global peace, which are directly useful for all nations. However, the latter examples are subjected to constraints which influence or are influenced by the institutions which make the decisions about them. This article proposes a review of the basic economic concepts concerning the production of international public goods and it applies them, in a still embryonic way, to the case of peace and security in Southern Africa. –Summary AFRI-2003