The life of Joseph Smith from 1827 to 1830, when he was 22–25 years old, begins in late 1827, after Smith announced he had obtained a book of golden Plates buried in a hill near his home in Manchester, New York (near Palmyra village). Because of opposition by former treasure-seeking colleagues who believed they owned a share of the golden plates, Smith prepared to leave the Palmyra area for his wife's home town of Harmony, Pennsylvania (now Oakland). From late 1827 to the end of 1830, Smith dictated what he stated was a translation of ancient writing on the plates, published the dictation as the Book of Mormon, and established the Church of Christ.

To dictate the Book of Mormon, Smith enlisted the assistance of Martin Harris, a wealthy Palmyra landowner who acted as Smith's scribe. Smith said that he used seer stones (one set of which Smith later called the Urim and Thummim) to translate the plates. Translation ceased, however, when Harris lost 116 manuscript pages of uncopied text. Translation resumed in earnest when Smith was joined in May 1829 by a Smith family associate named Oliver Cowdery. Translation was completed near the end of July 1829, and the resulting manuscript was published as the Book of Mormon on March 26, 1830, in Palmyra.

By the time the Book of Mormon was published, Smith had baptized several followers who called themselves the Church of Christ. On April 6, 1830, Smith and five others formally established the Church of Christ in western New York. Among the most notable early converts was Sidney Rigdon, a Disciples of Christ (Campbell Movement) minister from Kirtland, Ohio, who already shared many early beliefs of the Latter Day Saint movement. With Rigdon came most of Rigdon's congregation, and at the end of 1830, Smith decided that all members of his new church should move to Kirtland.

Dictation of the Book of Mormon

Recruitment of Martin Harris When Smith said he had obtained the book of golden plates from the Angel Moroni (see Early life of Joseph Smith), he also said the angel commanded him "that the plates must be translated, printed and sent before the world". To do so, however, he needed money, and at the time he was penniless. Therefore, Smith sent his mother to the home of Martin Harris, a local landowner said at the time to be worth about $8,000 to $10,000.

Harris had been a close confidant of the Smith family since at least 1826, and he may have heard about Smith's attempts to obtain the plates from the angel even earlier from Joseph Smith Sr. He was also a believer in Smith's powers with his seer stone. When Lucy visited Harris, he had heard through the grapevine in Palmyra that Smith said he had discovered a book of Golden Plates, and he was interested in finding out more. Thus, at Lucy Smith's request, Harris went to the Smith home, heard the story from Smith, and hefted a glass box that Smith said contained the plates. Smith convinced Harris that he had the plates, and that the angel had told him to "quit the company of the money-diggers". Convinced, Harris immediately gave Smith $50,; and committed to sponsor the translation of the plates.

The money provided by Harris was enough to pay all of Smith's debts in Palmyra, and for him to travel with his new bride Emma and all of their belongings to Harmony Township, Pennsylvania (now in Oakland Township), where they would be able to avoid the public commotion in Palmyra over the plates. Thus, in late October 1827, they moved to Harmony, with the glass box purportedly holding the plates hidden during the trip in a barrel of beans.

Early transcription and dictation When Joseph and Emma arrived in Harmony, they stayed temporarily in the home of Emma's father Isaac Hale, while Hale set them up in a home on an adjoining property a few hundred yards from the Susquehanna River. Skeptical that Smith had found golden plates, Hale asked to see them, but was only allowed to lift the glass box in which Smith said they were kept. Nevertheless, Hale refused to allow the plates in his home if he could not see them, so the glass box was hidden in the woods nearby, where the plates are said to have remained during much of the translation process that followed.;

After a short stay in the Hale home, Joseph and Emma arranged to live in a house moved onto the Hale property. Emma said that for at least part of the time, Joseph kept the plates in this house on a table, wrapped in a linen tablecloth. Beginning in December 1827, Smith began transcribing the characters he said were engraved on the plates, and dictating what he said was a translation of some of them. While transcribing, he reportedly sat behind a curtain and looked at the plates through the Urim and Thummim, passing the written transcriptions to Emma, who was sitting on the other side of the curtain. Eventually, after some transcription, he began to dictate what he said was a translation of the plates to Emma or her brother Reuben. To translate, he reportedly "put the urim and thummim into his hat and Darkened his Eyes than [sic] he would take a sentance [sic] and it would apper [sic] in Brite [sic] Roman Letters. Then he would tell the writer and he would write it." Reportedly, Smith did not need the physical presence of the plates to create the translation,; and the plates remained in the nearby woods during the translation.

Harris came to assist with the translation in February 1828. Around this time, Smith reportedly confided to Emma's uncle that he had doubts about whether or not he should translate the plates, because despite the commandment from God, "he was afraid of the people". Thus, when Harris arrived, he reportedly had to convince Smith to continue translating, saying, "I have not come down here for nothing, and we will go on with it".

Visit to Charles Anthon and others In February 1828, after visiting Smith in Harmony, Harris took a sample of the characters Smith had copied to a few prominent scholars, including Charles Anthon.; He said Anthon initially authenticated the characters and their translation, but then retracted his opinion after learning that Smith claimed to have received the plates from an angel.; Anthon denied Harris's account of the meeting, claiming instead that he had tried to convince Harris that he was the victim of a fraud. (Anthon's description of his meeting with Harris). But see (arguing that Anthon's initial assessment was likely more positive than he would later admit). In any event, Harris returned to Harmony in April 1828 and began serving as Smith's scribe.

Harris also visited several other well-known scholars, including at least Luther Bradish in Albany, New York and Samuel L. Mitchill of New York City.; The purpose of these visits was to see if they could translate or authenticate some of the transcribed characters, but Harris was unable to get any of the scholars' help or backing.

Loss of 116 manuscript pages

After visiting his home in Palmyra, Harris then returned to Harmony in the middle of April 1828 and began acting as Smith's scribe while Smith dictated what he later would call the Book of Lehi. Harris reported that for at least part of Smith's early translation, Smith used his seer stone to translate, rather than the Urim and Thummim, because the stone was more convenient. Smith also at least sometimes made use of a curtain; Harris stated that one time during the translation, Smith raised a curtain between him and Harris, because "the presence of the Lord was so great", or sometimes Smith dictated to Harris from upstairs or from a different room.

By the middle of June 1828, Smith had dictated about 116 manuscript pages of text, beginning with a story about a man named Lehi in Jerusalem, and ending with a story about King Benjamin, one of his descendants, in the Americas. Harris, however, was having marital problems with his wife Lucy, who was upset about not being able to see the plates. Hoping to appease her, and to quell his own doubts, Harris convinced a reluctant Smith to allow him to take the 116 manuscript pages with him on a visit back home in Palmyra. Because the manuscript was the only copy, however, Smith made Harris sign a written oath that he would show the pages only to five specified people in his family.;

While Harris visited Palmyra, Emma gave birth to the young couple's first child, but the boy was deformed and stillborn, leaving Emma deathly ill for about two weeks. Not hearing word from Harris for three weeks, Smith traveled in July 1828 to Palmyra and learned that Harris had lost the manuscript pages, and had been avoiding him. Despite his oath, Harris had been exhibiting the manuscript to numerous visitors, and somehow it had disappeared from the drawer where he kept it.

Smith was despondent over losing his child and the manuscript. He had had great hopes for his first-born child, reportedly telling people that the child would see the plates, and that he would assist in the translation. After returning to Harmony without Harris, Smith dictated to Emma his first written revelation, which rebuked him for losing the manuscript pages, but pinned most of the blame upon Harris.

During this period, Smith also reportedly joined a local Methodist Episcopal Church Sunday school class in Harmony. This church was attended by Emma's family, and led by Nathaniel Lewis, Isaac Hale's brother-in-law. His membership, however, was resisted by several members who were aware of his treasure hunting activities, and Smith voluntarily withdrew his membership.

Resumption of dictation

As part of the penalty for losing the manuscript, Smith said the angel took away the Urim and Thummim, returning it once again on September 22, 1828, the autumn equinox and the anniversary of the day he first received the plates. Smith said the angel also temporarily took back the plates during that time.;

By February 1829, Smith had begun dictating sporadically with Emma as scribe. Smith resumed the translation beginning at the story of King Benjamin now found in the Book of Mosiah, where Smith had left off with Harris before losing the 116 pages. In February, when Smith's parents visited Harmony, and Smith dictated a revelation for his father, an optimistic description of the translated book as a "marvelous work…about to come forth among the children of men".

According to Emma, Smith no longer used the Urim and Thummim in the process after the loss of the 116 manuscript pages; rather, he began using exclusively his dark seer stone. He dictated after sitting "with his face buried in his hat with the seer stone in it, and dictating hour after hour with nothing between us". While looking at the stone, he "rest[ed] his elbows upon his knees", and drew the hat "closely around his face to exclude the light", so that the "spiritual light" would shine.

The dictation during this time was sporadic, in part because Emma was busy running the household, and Joseph was working outside the home. They received some support for the translation, however, including money for paper, from Joseph Knight Sr., Smith's associate from his treasure hunting expeditions.