Co-management-the sharing of responsibilities between governmental institutions and groups of resource users-is rapidly gaining popularity in Asia. In many countries environmental management is reformulated from exclusive state control to various kinds of joint management in which local communities, indigenous peoples, and nongovernmental organizations share authority and benefits with governmental institutions. Combining case studies of experiments with co-management in a number of different countries with more reflective contributions, this in-depth analysis addresses the underlying assumptions and problems in the practical implementation of co-management practices.