Non-governmental organizations have played a very important role in the development of environmental policy in many countries as well as the emergence of global awareness about the state of environment. This organization can be grouped into following three categories:
1. Specialized agencies with restricted membership consisting primarily of scientific and professional members. Like International Council of Scientific Unions (ICSU) or International Union for Conservation of Nature and Natural Resources (IUCN).
2. Institutes and Centers devoted to the task of collection of information, research and consultation such as International Institute for Environment and Development, the Institute of European Environmental Policy etc.
3. Activist Organizations with open membership which are devoted to the cause of raising support and consensus for wildlife protection, conservation of resources and improvement in the quality of environment. These include organizations like Sierra, Club National Audubon Society, and Bombay Natural History Society etc.
Non-governmental organizations usually consist of volunteers or group of individuals genuinely interested in the cause of conservation of wildlife, natural resources and protection of the environment for which they generate their own resources, contributory funds, grants etc.
They are often able to manage things more efficiently and easily than governments which work with authority. They have played a great role in the development of public awareness about environmental matters and much of evolution of national and international environmental co-operation can be attributed to this public opinion which shapes the policies of a country.