Membership in the United Nations (U.N.) has been an issue of ongoing interest for Congress. Over the years, Members have focused on the process and criteria for U.N. membership, as well as on U.S. policy and roles in determining membership. Currently, the United Nations has 193 members. The organization also has two non-member observer states, the Holy See (Vatican) and "Palestine," which have standing invitations to participate as observers in the sessions and work of the U.N. General Assembly. Each of the U.N. system's 15 specialized agencies—which are independent international intergovernmental organizations with their own constitutions, rules, and budgets—have different criteria and processes for membership. Examples of specialized agencies include the Food and Agriculture Organization (FAO), U.N. Educational Scientific, and Cultural Organization (UNESCO), and World Health Organization (WHO). Under Article 4 of the U.N. Charter, the U.N. Security Council and U.N. General Assembly are the primary bodies involved in the process for considering U.N. membership applications. Security Council recommendations on membership are subject to veto by any of the five permanent members. As a member of the P-5, the United States plays a key role in determining U.N. membership. It has less influence on membership decisions in the U.N. specialized agencies, where each member country has one vote and there is no veto power. Any position on membership the United States takes in both the United Nations and its specialized agencies lies primarily with the executive branch, which represents the United States in U.N. fora. Generally, congressional activities related to U.N. membership have focused on supporting or opposing the membership of specific states or groups—including Israel, Kosovo, Montenegro, the Palestine Liberation Organization (PLO), South Africa, and Taiwan, among others. This report highlights key steps in the process for attaining membership in the United Nations and its specialized agencies. It discusses the capacities associated with U.N. membership and observer status, as well as criteria for and implications of membership. It also examines related U.S. legislation and recent congressional and Obama Administration actions. For an analysis of country or organization-specific aspects of U.N. or specialized agency membership, including U.S. policy, see CRS Report RL34074, The Palestinians: Background and U.S. Relations , by [author name scrubbed]; CRS Report R41952, U.S.-Taiwan Relationship: Overview of Policy Issues , by [author name scrubbed] and [author name scrubbed]; and CRS Report R42999, The United Nations Educational, Scientific, and Cultural Organization (UNESCO) , by [author name scrubbed] and [author name scrubbed]. The criteria and process for admitting new U.N. members were established in 1945 by the 51 original members of the United Nations in Article 4 of the U.N. Charter. U.N. membership decisions are determined by the General Assembly on the recommendation of the Security Council. Membership is open to all "peace-loving states" that accept the obligations contained in the Charter and, in the judgment of the organization, are able and willing to carry out such obligations. Many experts contend that the imprecise nature of these criteria has allowed member states to broadly interpret the conditions for membership, in some cases causing political considerations to have significant weight on membership decisions. The pace at which new members have been admitted to the United Nations has generally reflected the geo-political circumstances of the time. For example, Cold War tensions contributed to the limited number of new members admitted during the organization's first decade. Both Eastern and Western bloc countries were concerned that new members might strengthen the voting power of the other bloc; consequently, just nine states were admitted between 1945 and 1954 (see Figure 1 ). From the mid-1950s through the 1970s, U.N. membership more than doubled as former European colonies in Africa were admitted. Another wave of new members resulted from the dissolution of the former Soviet Union, Yugoslavia, and Czechoslovakia in the 1990s and early 2000s. The four states most recently admitted as members were Switzerland (2002), Timor-Leste (2002), Montenegro (2006), and South Sudan (2011). A key area of ongoing debate regarding U.N. membership is the organization's possible role in determining statehood. By international practice, a state is generally understood to be "an entity that has a defined territory and a permanent population, under the control of its own government, and that engages in, or has the capacity to engage in, formal relations with other such entities." On the one hand, the United Nations—as an organization of independent states—does not recognize states; rather, states recognize states. As such, many experts and observers, including the United Nations itself, argue that the organization does not have the authority to recognize either a state or government. On the other hand, many analysts agree that U.N. membership is an acknowledgement by U.N. members that an entity has satisfied the requirements of statehood. It provides governments with legitimacy, not only internationally, but also domestically. For many countries, membership in the United Nations provides an equal voice in U.N. bodies like the General Assembly, an international platform to advocate and pursue national and foreign policy objectives, and the opportunity to receive or provide technical or development assistance through multilateral mechanisms. Consequently, obtaining U.N. membership is often a priority for new countries, territories, organizations, or entities (hereinafter referred to as "entities" for the purpose of this report) aiming to obtain statehood. The circumstances under which a state obtains U.N. membership can vary. The original 51 members of the organization include many of the Allied nations of World War II that had either signed the United Nations Declaration in 1942, or participated in the founding United Nations Conference in San Francisco in 1945. The remaining 142 members were accepted for membership under the criteria and processes outlined in the Charter and the Rules of Procedure for both the General Assembly and the Security Council. Examples of circumstances under which these states obtained U.N. membership are described below, and in some cases may overlap. Some members, sometimes referred to as existing states , were not among the original 51 U.N. members; they were, however, subsequently admitted to the organization. Examples include Barbados, Brazil, Italy, Japan, Tunisia, and Nigeria. Other members are or were divided states . Such states, which were divided because of the East-West conflict, have generally obtained U.N. membership after the claims of various sides had been determined in favor of either division or reunification. Examples include the Federal Republic of Germany and the German Democratic Republic (now Germany), North and South Korea, and the Republic of Vietnam and Democratic Republic of Vietnam (now Vietnam). Some members have been admitted after the secession or partition of a state that was already a U.N. member. In such cases, the seceding entity reapplied for membership. Examples include the partitions of Pakistan and India and Pakistan and Bangladesh, and the admission of Estonia, Latvia, and Lithuania as new U.N. members after the breakup of the Soviet Union. In some cases, two existing member states have merged . In practice, the process for admitting such members has been flexible; the newly merged states did not have to reapply for membership. Examples include East and West Germany (Germany) and the Yemen Arab Republic and the People's Democratic Republic of Yemen (Yemen). One state, Indonesia, withdrew and re-entered the United Nations in the mid-1960s. The General Assembly and Security Council treated the withdrawal as if it were a "temporary 'inactive' membership" that ended cooperation with the organization, rather than the country's membership. The Assembly and Council provided a standing invitation for Indonesia to "reactivate" its membership at any time. Indonesia eventually rejoined the organization without reapplying for admission. The criteria for U.N. membership are outlined in Article 4 of the U.N. Charter (see text box ), and can be divided into four key elements. First, an applicant must be a state. An entity applying for U.N. membership must meet the requirements of statehood under international law (a defined territory, a permanent population, and independent governance), be recognized by other states, and have the capacity to conduct diplomacy with other countries. Second, an applicant must be "peace-loving." This criterion has been used to evaluate an applicant's past and current conduct. The concept of a "peace-loving" state in many ways reflects the United Nations' purpose of maintaining international peace and security. Third, an applicant must declare that it accepts obligations contained in the U.N. Charter by (1) consenting to be bound by the U.N. Charter, a legally binding international treaty; and (2) attaching a formal declaration to its U.N. membership application. Fourth, an applicant must be willing and able to carry out U.N. Charter obligations. U.N. members have identified several indicators to consider when evaluating this criteria application: including the maintenance of friendly relations with other states; the fulfillment of international obligations; and the use of peaceful dispute settlement under international law. The Security Council and General Assembly are the primary bodies that consider U.N. membership applications under Article 4 of the U.N. Charter. The rules of procedure for both the Security Council and the General Assembly set forth the details of this process. Applications for membership are submitted by the requesting state to the U.N. Secretary-General, who then forwards them to the Assembly and the Council. The amount of time it takes for an application to move through the process varies. In some cases, membership may be granted within weeks or months, while in other cases an application may remain pending indefinitely.