The United Nations (UN) is the new global organization for the maintenance of international peace and security founded in 1945 as the post Second World War universal organization.

In the framework of the UN, regionalism has two meanings. First, there are regional groupings and commissions starting their life early in the history of the UN and recognized during 1960s as a means to facilitate UN’s work in several areas from maintaining international peace and security to cooperation in economic, social and cultural issues. Secondly, there are other international organizations, some of which are regional ones, and collaboration between them and the universal organization.

Regionalism has three displays in the UN system: regional economic commissions (linked to the Economic and Social Council, ECOSOC), regional electoral groupings (linked to the General Assembly and the Security Council), and cooperation with the regional arrangements or agencies as envisaged at Chapter VIII with the aim of maintenance of international peace and security.

There were three changes made at the San Francisco Conference regarding the regional groupings or agencies. First, a provision stressing the desirability of using regional arrangements and agencies for the peaceful settlement was inserted. Second, the requirement of Security Council authorization for enforcement action under regional arrangement were waived in the case of measures taken against an enemy state under Article 107 of the Charter or under “regional arrangements directed against the renewal of aggressive policy” by any such state. Third, by the terms of Article 51 of the Charter, “the inherent right of individual or collective self-defence if an armed attack occurs against a Member of the United Nations” was safeguarded.

The aim of regionalism is to pursue and promote common goals in one or more areas.

A regional agency is a regional organization with legal personality and an organizational structure located in a member country.

A regional arrangement is a grouping of states under a treaty for a specified common purpose without any organization to personify that arrangement.

These five regional groups are Africa (GAFS), Asia-Pacific (GASS), Eastern Europe (EEC), Latin America and Caribbean (GRULAC), Western Europe and Other States (WEOG).

Israel became a WEOG member in 2000.

Estonia became a member of the UN in 1991.

Estonia became a member of the UN in 1991, but joined the EEC in 2004.

The purpose of these groupings is to allocate seats on the UN bodies equitably

UNICEF divides its members into regional groups differently: Central and Eastern Europe and CIS States, East Asia and the Pacific, Eastern and Southern Africa, Industrialized Countries, Latin America and the Caribbean, Middle East and North Africa, South Asia, West and Central Africa.

There are five regional bodies established under the ECOSOC:
- Economic Commission for Europe (ECE), established in 1947, Geneva;
- Economic and Social Commission for Asia and the Pacific (ESCAP), established in 1947 as Economic Commission for Asia and the Far East and renamed in 1974, Bangkok,
- Economic Commission For Latin America and the Caribbean (ECLAC),established in 1948, Santiago,
- Economic Commission for Africa (ECA), established in 1958, Addis Ababa,
- Economic and Social Commission for Western Asia (ESCWA), which replaced the former UN Economic and Social Office in Beirut in 1973, Baghdad.

There are three types of membership, namely, full membership, associate membership and observer status.

Although there are some small differences, principal functions and purposes of the commissions are as follows:
- to initiate and participate in measures for facilitating regional economic development,
- raise the level of economic activity in the respective region,
- maintain and strengthen economic relationships among the states of the region and with other states,
- to investigate and study economic and technological problems and developments,
- to collect, evaluate and disseminate economic, technological and statistical information.

It was established in 1948.

The Security Council is to encourage the settlement of local disputes by regional means and to use regional arrangement for enforcement action.

A regional organization must have certain characteristics. First, it has to be smaller in number than the UN, territorially linked to be able to have an effective dispute settlement mechanism, have the maintenance of peace and security as one of its main tasks and both its constitution and activities must be in conformity with the UN’s purposes and principles.

Peacekeeping operations became a new area of cooperation between the UN and regional arrangements in the 1990s.