A pioneer is a volunteer Bahá'í who leaves his or her home to journey to another place (often another country) for the purpose of teaching the Bahá'í Faith. The act of so moving is termed pioneering. Bahá'ís refrain from using the term "missionary". The first pioneer to enter a country or region mentioned in `Abdu'l-Bahá's Tablets of the Divine Plan is given the title of Knight of Bahá'u'lláh.
During the Ten Year Crusade which ran from 1953 to 1963, hundreds of pioneers settled in countries and territories throughout the world, which eventually led to the establishment of 44 new National and Regional Spiritual Assemblies and the increase in the Bahá'í population.
Teaching work 
The teaching work done by pioneers was done in many different ways including, but not limited to
- Conversation with people who are receptive to the teachings of the Bahá’í Faith.
- Firesides: meetings held in one's home to which those interested in the Bahá’í Faith are invited.
- Public talks: Lectures given about the Bahá’í Faith.
Shoghi Effendi, the Guardian of the Bahá’í Faith, has written:
- "An effort, moreover, can and should be made, not only by representative Bahá'í bodies, but also by prospective teachers, as well as by other individual believers, deprived of the privilege of visiting those shores or of settling on that continent, to seize every opportunity that presents itself to make the acquaintance, and awaken the genuine interest, of such people who are either citizens of these countries, or are in any way connected with them, whatever be their interests or profession. Through the kindness shown them, or any literature which may be given them, or any connection which they may establish with them, the American believers can thereby sow such seeds in their hearts as might, in future circumstances, germinate and yield the most unexpected results.
Teaching versus proselytization 
For Bahá'ís, pioneering refers to something similar to missionary work. However, Bahá'ís do not consider pioneering to be proselytism, a word which often implies the use of coercion to convert someone to a different religion.
- "Care, however, should, at all times, be exercised, lest in their eagerness to further the international interests of the Faith they frustrate their purpose, and turn away, through any act that might be misconstrued as an attempt to proselytize and bring undue pressure upon them, those whom they wish to win over to their Cause."
- "It is true that Bahá'u'lláh lays on every Bahá'í the duty to teach His Faith. At the same time, however, we are forbidden to proselytize, so it is important for all the believers to understand the difference between teaching and proselytizing. It is a significant difference and, in some countries where teaching a religion is permitted, but proselytizing is forbidden, the distinction is made in the law of the land. Proselytizing implies bringing undue pressure to bear upon someone to change his Faith. It is also usually understood to imply the making of threats or the offering of material benefits as an inducement to conversion. In some countries mission schools or hospitals, for all the good they do, are regarded with suspicion and even aversion by the local authorities because they are considered to be material inducements to conversion and hence instruments of proselytization."
The following is a letter written on behalf of Shoghi Effendi to an individual:
- "He sees no objection to the word Missionary appearing on your passport as long as it is clearly understood what kind of a ‘missionary’ a Bahá’í pioneer is. In the best and highest sense of the term it certainly could be applied to our teachers. Unfortunately this word has often been associated with a narrow-minded, bigoted type of proselytizing quite alien to the Bahá’í method of spreading our teachings."
Widespread effect 
During Bahá'u'lláh's lifetime (died 1892) he encouraged some of his followers to move to India. When the religion began to grow in India, other Bahá'ís moved on - for example entering Vietnam and other places in 1950s. During the 1950s and 1960s the Bahá'í Faith spread rapidly in Vietnam, and the nearby countries of Indonesia, Malaysia, and the Philippines. From 1957 to 1963 the Bahá'í community in Vietnam had more than tripled.
The Tablets of the Divine Plan to the followers of the religion in the North America, especially to the United States, in 1916-1917 by `Abdu'l-Bahá, head of the religion until 1921 when he died, asking the followers of the religion to travel to other countries; these letters were compiled together in the book titled Tablets of the Divine Plan. Their publication was delayed in the United States until 1919 — after the end of the First World War and the Spanish flu. Following their publication the first Bahá'í permanent resident in South America, Leonora Armstrong, arrived in Brazil in 1921. Shoghi Effendi, who was named `Abdu'l-Bahá's successor, wrote a cable on May 1, 1936 to the Bahá'í Annual Convention of the United States and Canada, and asked for the systematic implementation of `Abdu'l-Bahá's vision to begin. In his cable he wrote:
"Appeal to assembled delegates ponder historic appeal voiced by 'Abdu'l-Bahá in Tablets of the Divine Plan. Urge earnest deliberation with incoming National Assembly to insure its complete fulfillment. First century of Bahá'í Era drawing to a close. Humanity entering outer fringes most perilous stage its existence. Opportunities of present hour unimaginably precious. Would to God every State within American Republic and every Republic in American continent might ere termination of this glorious century embrace the light of the Faith of Bahá'u'lláh and establish structural basis of His World Order."
Following the May 1st cable, another cable from Shoghi Effendi came on May 19th calling for permanent pioneers to be established in all the countries of Latin America. The Bahá'í National Spiritual Assembly of the United States and Canada was appointed the Inter-America Committee to take charge of the preparations. During the 1937 Bahá'í North American Convention, Shoghi Effendi cabled advising the convention to prolong their deliberations to permit the delegates and the National Assembly to consult on a plan that would enable Bahá'ís to go to Latin America. In 1937 the First Seven Year Plan (1937-44), which was an international plan designed by Shoghi Effendi, gave the American Bahá'ís the goal of establishing the Bahá'í Faith in every country in Latin America. With the spread of American Bahá'ís in Latin American, Bahá'í communities and Local Spiritual Assemblies began to form in 1938 across Latin America. The first pioneer to Chile arrived in 1940 when her ship docked at Arica. After arriving in Panama in 1940, the first Guaymí Bahá'í converted in the 1960s. In 1985-6 the "Camino del Sol" project included indigenous Guaymí Bahá'ís of Panama traveling with the Venezuelan indigenous Carib speaking and Guajira Bahá'ís through the Venezuelan states of Bolívar, Amazonas and Zulia sharing their religion.
In 1946, a great pioneering movement began with sixty percent of the British Bahá'í community eventually relocating. Internationally this effort would take the Bahá'í Faith to Scotland, Wales, and Ireland and raising the numbers of Local Assemblies in the British Isles. In 1950-1 the Baha'is of the British Isles pioneered to Tanganyika, Uganda, and Kenya. On August 3, 1951 pioneers arrived in Kampala from which pioneers went to French Equatorial Africa, and Cameroon and so on. This led to a wide-scale growth in the religion across Sub-Saharan Africa.
- Effendi, Shoghi (1938). The Advent of Divine Justice. Wilmette, Illinois, USA: Bahá'í Publishing Trust. p. 65. ISBN 0-87743-195-7.
- Letter from the Universal House of Justice, 1982 Jan 03, Teaching vs. Proselytizing.
- Letter written by Shoghi Effendi on February 7, 1945 published in Effendi, Shoghi; The Universal House of Justice (1983). In Hornby, Helen (Ed.). Lights of Guidance: A Bahá'í Reference File. Bahá'í Publishing Trust, New Delhi, India. ISBN 81-85091-46-3.
- Bahá'í History by Moojan Momen and Peter Smith
- Sarwal, Anil (1989). "Shirin Fozdar: An Outstanding Pioneer". Bahá'í Digest. Retrieved 2008-02-23.
- Momen, Moojan (1996). "The Bahá'í Today". A Short Introduction to the Bahá'í Faith.
- Rabbani, R. (Ed.) (1992). The Ministry of the Custodians 1957-1963. Bahá'í World Centre. pp. 138, 140, 360. ISBN 0-85398-350-X.
- Bahá'í International Community (1996). "Brazilian parliament honors leading Bahá'í dignitary". OneCountry 8 (2).
- Lamb, Artemus (November 1995). The Beginnings of the Bahá'í Faith in Latin America:Some Remembrances, English Revised and Amplified Edition. 1405 Killarney Drive, West Linn OR, 97068, United States of America: M L VanOrman Enterprises.
- Effendi, Shoghi (1947). Messages to America. Wilmette, Illinois, USA: Bahá'í Publishing Committee. p. 6. OCLC 5806374. Unknown parameter
- Ruhe-Schoen, Janet (2007). "An Enchantment of the Heart - A Portrait of Marcia Steward, Knight of Bahá’u’lláh, First Bahá’í Pioneer to Chile and the Marshall Islands". The Chilean Temple Initiative (National Spiritual Assembly of the Baha'is of the United States).
- "Comunidad Bahá'í de Panamá". Official Website of the National Spiritual Assembly of the Bahá'ís of Panama. Comunidad Nacional Bahá'í de Panamá. Retrieved 2008-06-30.
- International Community, Bahá'í (October–December 1994). "In Panama, some Guaymis blaze a new path". One Country 1994 (October–December).
- "Historia de la Fe Bahá'í en Venezuela". La Fe Bahá'í en Venezuela. National Spiritual Assembly of Venezuela. Retrieved 2008-07-05.
- U.K. Bahá'í Heritage Site. "The Bahá'í Faith in the United Kingdom - A Brief History". Retrieved 2008-02-18.[dead link]
- Mughrab, Jan (2004). "Jubilee Celebration in Cameroon". Journal of the Bahá'í Community of the United Kingdom of Great Britain and Northern Ireland 20 (5) (National Spiritual Assembly of the Bahá'ís of the United Kingdom).[dead link]
- "Overview Of World Religions". General Essay on the Religions of Sub-Saharan Africa. Division of Religion and Philosophy, University of Cumbria. Retrieved 2008-04-16.]