The United Nations Environmental Programme (UNEP) was founded in June 1972 as a result of the Stockholm Conference on the Human Environment.  

• The UNEP is the coordinating body for the United Nations’ environmental activities. It has played a significant role in identifying and analyzing global environmental problems, developing regional and international environmental programs and conventions, and promoting environmental science and information.  
• Among its most important tasks is assisting developing countries in implementing environmentally sound policies and practices. 
• Since 1997, in response to the environmental requirements of Agenda 21, UNEP has also published its Global Environment Outlook (GEO), a comprehensive report on global state of the environment. Its headquarters are in Nairobi, Kenya. 

Source: http://www.environmentandsociety.org/tools/keywords/united-nations-environmental-programme-unep-established