World War II led the dissolution of League of Nations. In 1945 the establishment of UNO was considered as the milestone in peace developments after World War II. UNO is an international organization with universal scope and responsibilities. The idea behind the formation of League of Nation was to bring peace and prosperity among member states by dissolving the disputes and conflicts between them. It has working organs dealing with different segments of life and society, working for health, education, poverty elimination, unemployment, child labor and women rights and sustainable development etc.

The Aftermath of WW II was the right time for the establishment of UNO because the nations were trying to recover from the horrible effects of war and there always prevails the looming shadows of war as a result of Cold War animosity between US and USSR. However, the role of UNO was not as much appreciating. The League of Nations has sixty three members till its dissolution whereas, when UN came into force fifty one nations has signed the charter and now it has one eighty two member states.

UNO survived until the end of Cold War however it has to face the new challenges in unipolar world. The new world order was enough to shrink the activity and scope of UNO. S.J. Michalck (1971. P.387) has written that the success or failure of International organizations stem not so much from their formal Legal covenants as from changing configurations and distributions of power systematic issues and forces and the attitudes and resources of member states this is the reason that UNO is not able to stop the war because of interventions of influential superpowers.

Beside all this, UNO is the world wide organization, serving in member countries where weak democracies and internal conflicts and in some cases external interventions are going on. The initiative taken by UNO, like sustainable development program regards too much. It has effectively working for humanitarian purposes in Africa, Asia and Latin America as it ever served before.