What are UN Specialized Agencies and how many are there?

UN specialized agencies are international organizations working with the UN, in accordance with relationship agreements between each organization and the UN. UN Specialized Agencies admit members and appoint their administrative head in accordance with their founding documents and rules of procedure. 

There are 17 Specialized Agencies. Reference is sometimes made to 15 Specialized Agencies because the World Bank Group, which is now treated as one organization, is composed, in part, of three Specialized Agencies.

Agreements between the United Nations and the Specialized Agencies are generally found in the UN Treaty Series.

• Food and Agriculture Organization of the United Nations (FAO)
  • Relationship Agreement with UN (1946): 1 UNTS 207
• International Civil Aviation Organization (ICAO)
  • Relationship Agreement with UN (1947): 8 UNTS 315
• International Fund for Agricultural Development (IFAD)
  • Relationship Agreement with UN (1977): 1080 UNTS 331
• International Labour Organization (ILO)
  • Relationship Agreement with UN (1946): 1 UNTS 183
• International Monetary Fund (IMF)
  • Relationship Agreement with UN (1947): 16 UNTS 325
• International Maritime Organization (IMO)
  • Relationship Agreement with the UN (1959): 324 UNTS 273
• International Telecommunication Union (ITU)
  • Relationship Agreement with UN (1949): 30 UNTS 316
• United Nations Educational, Scientific and Cultural Organization (UNESCO)
  • Relationship Agreements with UN (1946): 1 UNTS 233, 21 UNTS 341
• United Nations Industrial Development Organization (UNIDO)
  • Relationship Agreement with UN (1985): 1412 UNTS 305
• World Tourism Organization (UNWTO)
  • Relationship Agreement with UN: A/RES/58/232 of 23 December 2003
• Universal Postal Union (UPU)
  • Relationship Agreement with UN (1948): 19 UNTS 219
• World Health Organization (WHO)
  • Relationship Agreement with UN (1948): 19 UNTS 193
• World Intellectual Property Organization (WIPO)
  • Relationship Agreement with UN (1974): A/RES/3346 (XXIX) of 17 Dec. 1974, 956 UNTS 405
• World Meteorological Organization (WMO)
  • Relationship Agreement with UN (1951): 123 UNTS 245
• World Bank Group
  • International Bank for Reconstruction and Development (IBRD) 
    • Relationship agreement with UN: 16 UNTS 341
  • International Finance Corporation (IFC, 1956)
    • Relationship agreement with UN: 265 UNTS 312
  • International Development Association (IDA, 1960)
    • Relationship agreement with UN: 394 UNTS 221

More treaties, letters, memoranda of understanding, and other agreements between the UN and Specialized Agencies can be found in the United Nations Juridical Yearbook. Chapter two of the Juridical Yearbook contains treaty provisions concerning the legal status of the United Nations and related Intergovernmental Organizations. This is a good place to look for any additional or subsequent agreements not published in the treaty series.

Specialized Agencies are mentioned in the Charter in 

• Chapter IX, International Economic and Social Co-operation
• Chapter X, The Economic and Social Council
• Article 58 of the Charter states that the UN will make "recommendations for the co-ordination of the policies and activities of the specialized agencies".  Coordination is facilitated through ECOSOC and the Chief Executives Board (CEB).