The "Wentworth letter" was a letter written in 1842 by Joseph Smith, founder of the Latter Day Saint movement, to "Long" John Wentworth, editor and proprietor of the Chicago Democrat. It outlined the history of the Latter Day Saint movement up to that time, and included Mormonism's Articles of Faith.
The letter was written in response to Wentworth's inquiry on behalf of one of his friends, George Barstow, who was writing a history of New Hampshire. The letter was first published on March 1, 1842, in the Times and Seasons in Nauvoo, Illinois.
A similar letter (with some slight revisions) was published by Daniel Rupp in 1844 in a book called An Original History of the Religious Denominations at Present Existing in the United States. wikisource:The Rupp Letter