"His letters to Bahá'í institutions and to Bahá'ís in general began almost at once, and many will be found in Bahá'í Administration, beginning January 21, 1922. Early or late, his communications were not merely writings, they were the dynamic that moved the Bahá'í world. These letters in effect built the Administrative Order, its most vital features being found there. They taught the Bahá'í Assemblies how to be, how to consult, what their duties were. The book also contains the Declaration of Trust and By-Laws drawn up by the international lawyer Mountfort Mills, carefully reviewed by Shoghi Effendi, and adopted in 1926 by the National Spiritual Assembly of the United States and Canada, at this time under one jurisdiction. (Khan, back in America by then. Shoghi Effendi wished all National Spiritual Assemblies to adopt, with necessary local adaptations, this Declaration of Trust and ByLaws, which set forth the character and objectives of Bahá'í communities worldwide." [Cited from AY304]

In the period from the inception of the Guardianship to 1937 Shoghi Effendi laid the foundation of the World Order of Bahá'u'lláh in conformity with the Will and Testament of 'Abdu'l-Bahá. Some of the major accomplishments were:
• Continued the translation work that began while he was still an assistant to 'Abdu'l-Bahá and later as a student at Oxford.
• Explained the principles and structure of the Administrative Order.
• Developed the constitutional structure of the local and national spiritual assemblies.
• Clarified the relationships of these assemblies with the community of believers and elucidate the manner of their election and operation.
• Emphasized that the Administrative Order was the channel through which the spirit of God would flow and instructed that they be ever watchful lest "the means supersede the end". [Pg209]
• Imparted the vision of the new world order through his letter which have become to be know as "The World Order Letters". [PG209-215]
  • 27 February, 1929: The World Order of Bahá'u'lláh
  • 21 March, 1930: The World Order of Bahá'u'lláh Further Considerations
  • 28 November, 1931: The Goal of the New World Order
  • 21 March, 1931: Golden Age of the Cause of Bahá'u'lláh
  • 21 April, 1933: America and the Most Great Peace
  • 8 February, 1934:The Dispensation of Bahá'u'lláh consisting of:
    • Bahá'u'lláh
    • Báb
    • Abdu'l‑Bahá
    • Administrative Order
  • 11 March, 1936: The Unfoldment of World Civilization
• 1988-12-29 — The Universal House of Justice issued a letter to the Bahá'ís in the United States published as Individual Rights and Freedoms in the World Order of Bahá'u'lláh. [Mess86-01p60]
• 2001-01-12 —
  The Administrative Order was further developed by the Universal House of Justice in its message to the Conference of the Continental Boards of Counselors of 9 January 2001 in which the concept of the "cluster" was first introduced. The cluster, a subdivision of the region, is to be formed on the basis of cultural, language, pattern of transport, infrastructure or the social life of the inhabitants.
  • In its message of 12 December 2011 the Universal House of Justice stated that the cluster should have three coordinators appointed by the Training Institute, one concerned with study circles, junior youth groups and a third for children's classes.
  • National Assemblies worldwide divided their countries into clusters on the basis of demographic, geographic, and socio-economic factors. A third of the resulting 15,000 clusters were in Africa.
  • TP176 says that there are now (17 January 2003) close to 17,000 clusters worldwide, excluding those countries where, for one reason or another, the operation of the Faith is restricted. The number of clusters per country varies widely—from India with its 1,580 to Singapore, which necessarily sees itself as one cluster. Some of the groupings are sparsely populated areas with only a few thousand inhabitants, while the boundaries of others encompass several million people. For the most part, large urban centers under the jurisdiction of one Local Spiritual Assembly have been designated single clusters, these in turn being divided into sectors, so as to facilitate planning and implementation.