Carey, the eldest of five children, was born to Edmund and Elizabeth Carey, who were weavers by trade in the village of Paulerspury in Northamptonshire. William was raised in the Church of England; when he was six, his father was appointed the parish clerk and village schoolmaster. As a child he was naturally inquisitive and keenly interested in the natural sciences, particularly botany. He possessed a natural gift for language, teaching himself Latin.

At the age of 14, Carey’s father apprenticed him to a shoemaker in the nearby village of Hackleton, Northamptonshire . His master, Clarke Nichols, was a churchman like himself, but another apprentice, John Warr, was a Dissenter. Through his influence Carey would eventually leave the Church of England and join with other Dissenters to form a small Congregational church in Hackleton. While apprenticed to Nichols, he also taught himself Greek with the help of a local villager who had a college education.

When Nichols died in 1779, Carey went to work for another local shoemaker, Thomas Old; he married Old’s sister-in-law Dorothy Plackett in 1781. Unlike William, Dorothy was illiterate; her signature in the marriage register is a crude cross. William and Dorothy Carey had seven children, five sons and two daughters; both girls died in infancy, as well as their son Peter, who died at the age of 5. Old himself died soon afterward, and Carey took over his business, during which time he taught himself Hebrew, Italian, Dutch, and French, often reading while working on his shoes.

Carey became involved with a local association of Particular Baptists that had recently formed, where he became acquainted with men such as John Ryland, John Sutcliff, and Andrew Fuller, who would become his close friends in later years. They invited him to preach in their church in the nearby village of Earls Barton every other Sunday. On 5 October 1783, William Carey was baptized by Ryland and committed himself to the Baptist denomination.

In 1785, Carey was appointed the schoolmaster for the village of Moulton. He was also invited to pastor the local Baptist church. During this time he read Jonathan Edwards' Account of the Life of the Late Rev. David Brainerd and the journals of the explorer James Cook, and became deeply concerned with propagating the Christian Gospel throughout the world. His friend Andrew Fuller had previously written an influential pamphlet in 1781 titled "The Gospel Worthy of All Acceptation", answering the hyper-Calvinist belief then prevalent in the Baptist churches, that all men were not responsible to believe the Gospel. At a ministers' meeting in 1786, Carey raised the question of whether it was the duty of all Christians to spread the Gospel throughout the world. J. R. Ryland, the father of John Ryland, is said to have retorted: "Young man, sit down; when God pleases to convert the heathen, he will do it without your aid and mine." However, Ryland's son, John Ryland Jr., disputes that his father made this statement.

In 1789 Carey became the full-time pastor of a small Baptist church in Leicester. Three years later in 1792 he published his groundbreaking missionary manifesto, An Enquiry into the Obligations of Christians to use Means for the Conversion of the Heathens. This short book consists of five parts. The first part is a theological justification for missionary activity, arguing that the command of Jesus to make disciples of all the world (Matthew 28:18-20) remains binding on Christians. The second part outlines a history of missionary activity, beginning with the early Church and ending with David Brainerd and John Wesley. Part 3 comprises 26 pages of tables, listing area, population, and religion statistics for every country in the world. Carey had compiled these figures during his years as a schoolteacher. The fourth part answers objections to sending missionaries, such as difficulty learning the language or danger to life. Finally, the fifth part calls for the formation by the Baptist denomination of a missionary society and describes the practical means by which it could be supported. Carey's seminal pamphlet outlines his basis for missions: Christian obligation, wise use of available resources, and accurate information.

Carey later preached a pro-missionary sermon (the so-called Deathless Sermon), using Isaiah 54:2-3 as his text, in which he repeatedly used the epigram which has become his most famous quotation: Carey finally overcame the resistance to missionary effort, and the Particular Baptist Society for the Propagation of the Gospel Amongst the Heathen (subsequently known as the Baptist Missionary Society and since 2000 as BMS World Mission) was founded in October 1792, including Carey, Andrew Fuller, John Ryland, and John Sutcliff as charter members. They then concerned themselves with practical matters such as raising funds, as well as deciding where they would direct their efforts. A medical missionary, Dr. John Thomas, had been in Calcutta and was currently in England raising funds; they agreed to support him and that Carey would accompany him to India.

Carey, his eldest son Felix, Thomas and his wife and daughter sailed from London aboard an English ship in April 1793. Dorothy Carey had refused to leave England, being pregnant with their fourth son and having never been more than a few miles from home; but before they left they asked her again to come with them and she gave consent, with the knowledge that her sister Kitty would help her give birth. En route they were delayed at the Isle of Wight, at which time the captain of the ship received word that he endangered his command if he conveyed the missionaries to Calcutta, as their unauthorized journey violated the trade monopoly of the British East India Company. He decided to sail without them, and they were delayed until June when Thomas found a Danish captain willing to offer them passage. In the meantime, Carey's wife, who had by now given birth, agreed to accompany him provided her sister came as well. They landed at Calcutta in November.

During the first year in Calcutta, the missionaries sought means to support themselves and a place to establish their mission. They also began to learn the Bengali language to communicate with the natives. A friend of Thomas owned two indigo factories and needed managers, so Carey moved with his family north to Midnapore. During the six years that Carey managed the indigo plant, he completed the first revision of his Bengali New Testament and began formulating the principles upon which his missionary community would be formed, including communal living, financial self-reliance, and the training of indigenous ministers. His son Peter died of dysentery, causing Dorothy to suffer a nervous breakdown from which she never recovered..

Meanwhile, the missionary society had begun sending more missionaries to India. The first to arrive was John Fountain, who arrived in Midnapur and began teaching school. He was followed by William Ward, a printer; Joshua Marshman, a schoolteacher; David Brunsdon, one of Marshman's students; and William Grant, who died three weeks after his arrival. Because the East India Company was still hostile to missionaries, they settled in the Danish colony at Serampore and were joined there by Carey on 10 January 1800.

Once settled in Serampore, the mission bought a house large enough to accommodate all of their families and a school, which was to be their principal means of support. Ward set up a print shop with a secondhand press Carey had acquired and began the task of printing the Bible in Bengali. In August 1800 Fountain died of dysentery. By the end of that year, the mission had their first convert, a Hindu named Krishna Pal. They had also earned the goodwill of the local Danish government and Richard Wellesley, then Governor-General of India.

The conversion of Hindus to Christianity posed a new question for the missionaries concerning whether it was appropriate for converts to retain their caste. In 1802, the daughter of Krishna Pal, a Sudra, married a Brahmin. This wedding was a public demonstration that the church repudiated the caste distinctions.

Brunsdon and Thomas died in 1801. The same year, the Governor-General founded Fort William, a college intended to educate civil servants. He offered Carey the position of professor of Bengali. Carey's colleagues at the college included pundit, whom he could consult to correct his Bengali testament. He also wrote grammars of Bengali and Sanskrit, and began a translation of the Bible into Sanskrit. He also used his influence with the Governor-General to help put a stop to the practices of infant sacrifice and suttee, after consulting with the pundits and determining that they had no basis in the Hindu sacred writings (although the latter would not be abolished until 1829).

Dorothy Carey died in 1807. She had long since ceased to be a useful member of the mission, and in fact was actually a hindrance to its work. John Marshman wrote how Carey worked away on his studies and translations, "while an insane wife, frequently wrought up to a state of most distressing excitement, was in the next room". In 1808 Carey re-married; his new wife Charlotte Rhumohr, a Danish member of his church was, unlike Dorothy, Carey's intellectual equal. They were married for 13 years until her death.

From the printing press at the mission came translations of the Bible in Bengali, Sanskrit, and other major languages and dialects. Many of these languages had never been printed before; William Ward had to create punches for the type by hand. Carey had begun translating literature and sacred writings from the original Sanskrit into English to make them accessible to his own countryman. On 11 March 1812, a fire in the print shop caused £10,000 in damages and lost work. Amongst the losses were many irreplaceable manuscripts, including much of Carey's translation of Sanskrit literature and a polyglot dictionary of Sanskrit and related languages, which would have been a seminal philological work had it been completed. However, the press itself and the punches were saved, and the mission was able to continue printing in six months. In Carey's lifetime, the mission printed and distributed the Bible in whole or part in 44 languages and dialects.

Also, in 1812, Adoniram Judson an American Congregational missionary enroute to India studied the scriptures on baptism in preparation for a meeting with Carey. His studies led him to become a Baptist. Carey's urging of American Baptists to take over support for Judson's mission, led to the foundation in 1814 of the first American Baptist Mission board, the General Missionary Convention of the Baptist Denomination in the United States of America for Foreign Missions, later commonly known as the Triennial Convention. Most American Baptist denominations of today are directly or indirectly descended from this convention.

In 1818, the mission founded Serampore College to train indigenous ministers for the growing church and to provide education in the arts and sciences to anyone regardless of caste or country. The King of Denmark granted a royal charter in 1827 that made the college a degree-granting institution, the first in Asia.

In 1820 Carey founded the Agri Horticultural Society of India at Alipore, Kolkata, supporting his enthusiasm for botany.

Carey's second wife, Charlotte, died in 1821, followed by his eldest son Felix. In 1823 he married a third time, to a widow named Grace Hughes.

Internal dissent and resentment was growing within the Missionary Society as its numbers grew, the older missionaries died, and they were replaced by less experienced men. Some new missionaries arrived who were not willing to live in the communal fashion that had developed, one going so far as to demand "a separate house, stable and servants." Unused to the rigorous work ethic of Carey, Ward, and Marshman, the new missionaries thought their seniors - particularly Marshman - to be somewhat dictatorial, assigning them work not to their liking.

Andrew Fuller, who had been secretary of the Society in England, had died in 1815, and his successor, John Dyer, was a bureaucrat who attempted to reorganize the Society along business lines and manage every detail of the Serampore mission from England. Their differences proved to be irreconcilable, and Carey formally severed ties with the missionary society he had founded, leaving the mission property and moving onto the college grounds. He lived a quiet life until his death in 1834, revising his Bengali Bible, preaching, and teaching students. The couch on which he died, on 9 June 1834, is now housed at Regent's Park College, the Baptist hall of the University of Oxford.

Biographies of Carey, such as those by F.D. Walker and J.B. Myers, only allude to Carey's distress caused by the mental illness and subsequent breakdown suffered by his wife, Dorothy, in the early years of their ministry in India. More recently, Beck's biography of Dorothy Carey paints a more detailed picture: William Carey uprooted his family from all that was familiar and sought to settle them in one of the most unlikely and difficult (for an uneducated eighteenth century English peasant woman) cultures in the world. Dorothy faced enormous difficulties in adjusting to all of this change; she failed to make the adjustment emotionally and ultimately, mentally, and her husband seemed to be unable to help her through all of this because he just did not know what to do about it. Carey even wrote to his sisters in England on 5 October 1795, that "I have been for some time past in danger of losing my wife. Jealousy is the great evil that haunts her mind."

Dorothy's mental breakdown ("at the same time William Carey was baptizing his first Indian convert and his son Felix, his wife was forcefully confined to her room, raving with madness") led inevitably to other family problems. Joshua Marshman was appalled by the neglect with which Carey looked after his four boys when he first met them in 1800. Aged 4, 7, 12 and 15, they were unmannered, undisciplined, and even uneducated.

Besides Iain Murray's study, The Puritan Hope, less attention has been paid in Carey's numerous biographies to his postmillennial eschatology as expressed in his major missionary manifesto, notably not even in Bruce J. Nichols' article "The Theology of William Carey." Carey was a Calvinist and a postmillennialist. Even the two dissertations which discuss his achievements (by Oussoren and Potts) ignore large areas of his theology. Neither mention his eschatological views, which played a major role in his missionary zeal. One exception, found in James Beck's biography of his first wife, mentions his personal optimism in the chapter on "Attitudes Towards the Future," but not his optimistic perspective on world missions, which he derived from Postmillenial theology.

Carey has at least four colleges named after him: William Carey International University in Pasadena, California, Carey Theological College in Vancouver, British Columbia, Carey Baptist College in Auckland, New Zealand, Carey Baptist Grammar School in Melbourne, Victoria and William Carey University, Hattiesburg, Mississippi. William Carey Academy of Chittagong, Bangladesh teaches both Bangladeshi and expatriate children, from Kindergarten to grade 10.

William Carey has been referred to as the "father of modern missions" and was a significance influence to the Protestant missionary movement of the 19th century.

Carey is honored with a feast day on the liturgical calendar of the Episcopal Church on October 19.

• William Carey website
• William Carey biographies

Carey, Eustace - Memoir of William Carey, D. D. Late missionary to Bengal, Professor of Oriental Languages in the College of Fort William, Calcutta. 1837, 2nd Edition, Jackson & Walford: London.

Carey, S. Pearce - William Carey "The Father of Modern Missions", edited by Peter Masters, Wakeman Trust, London, 1993 ISBN 1870855140