The "Word of Wisdom" is the common name of an 1833 section of the Doctrine and Covenants, a book considered by many churches within the Latter Day Saint movement to be a sacred text. The section defines beliefs regarding certain drugs, nutritious ingredients in general, and the counsel to eat meat sparingly; it also offers promises to those who follow the guidance of the Word of Wisdom.

As practiced by the Church of Jesus Christ of Latter-day Saints (LDS Church), the largest Latter Day Saint denomination, the Word of Wisdom explicitly prohibits the consumption of alcohol, tobacco, tea, coffee (with tea and coffee being labeled as "hot drinks"), and recreational drug use, and encourages healthy practices such as nutritious eating, the sparing consumption of meat, regular exercise, proper hygiene, and getting sufficient rest.

Compliance with the Word of Wisdom is necessary in the LDS Church to become a member and participate in various church functions, but a violation of the code is not normally cause for a church membership council.

Joseph Smith, founder of the Latter Day Saint movement, dictated the Word of Wisdom as a revelation from the Christian God on February 27, 1833. The Word of Wisdom was first published as a stand-alone broadsheet in December 1833. In 1835, it was included as Section LXXX (80) in the first edition of the Doctrine and Covenants. Brigham Young stated after Smith's death that the revelation was given in response to problems encountered while conducting meetings in the Smith family home:

When they assembled together in this room after breakfast, the first they did was to light their pipes, and, while smoking, talk about the great things of the kingdom, and spit all over the room, and as soon as the pipe was out of their mouths a large chew of tobacco would then be taken. Often when the Prophet [Joseph Smith] entered the room to give the school instructions he would find himself in a cloud of tobacco smoke. This, and the complaints of his wife at having to clean so filthy a floor, made the Prophet think upon the matter, and he inquired of the Lord relating to the conduct of the Elders in using tobacco, and the revelation known as the Word of Wisdom was the result of his inquiry.

— Brigham Young, Journal of Discourses, vol. 12, p. 158

In February 1834, Joseph Smith proposed a resolution before the high council of the church that stated, "No official member in this Church is worthy to hold an office after having the word of wisdom properly taught him; and he, the official member, neglecting to comply with and obey it." This resolution was accepted unanimously by the council. The charge of "not observing the Word of Wisdom" was later one of five leveled against David Whitmer (who was an apostle, and one of the Three Witnesses) on April 13, 1838, which led to his excommunication.

Joseph Smith is however recorded at various times drinking wine, beer, and tea, and using tobacco. One account by Amasa Lyman, a member of the First Presidency under Smith, reports that Smith once finished preaching a sermon on the Word of Wisdom and immediately afterward rode through the streets smoking a cigar. Similarly, Almon W. Babbitt stated "that he had taken the liberty to break the Word of Wisdom, from the example of President Joseph Smith, Jun., and others, but acknowledged that it was wrong" when he was brought before the church's high council on August 19, 1835, on the charge of "not keeping the Word of Wisdom". Joseph Smith had also been operating a hotel/tavern in Far West, Missouri, in 1838, and in June of that year, the high council of Far West felt compelled to remind Smith's family that there was a ban on the sale and consumption of "ardent spirits in the place".