Transnational commons, cross-border areas without well-defined property rights, have long been ignored in 'official' development economics. This volume redresses the balance by adopting an environmental approach which stresses the importance of shared natural resources and the links betweenacute poverty and environmental degradation. The Economics of Transnational Commons draws together eminent contributors from fields as diverse as law, population studies, social anthropology, biological sciences, and economics, to present authoritative accounts that combine empirical case-studies with rigorous theoretical foundations. Despitethe milti-disciplinary approach, the main focus of the articles is the same: that the reciprocal externalities and problems of free-riding created by any common resource are complicated in the case of transnational commons by difficulties in monitoring, enforcement, and unequal access toinformation. Often using theories of negotiation taken from game theory, the studies then suggest possible solutions, both at an institutional and educational level. In order to make these materials suitable for teaching purposes, the authors have been encouraged to survey their topics rather than present their most recent findings. A companion publication, The Environment and Emerging Development Issues Volumes 1-11 (edited by Dasgupta and Mahler), deals withnational environmental issues.