The Church Educational System (CES) Honor Code is a set of standards by which students and faculty attending a school owned and operated by the Church of Jesus Christ of Latter-day Saints (LDS Church) are required to live. The most widely known university that is part of CES that has adopted the honor code is Brigham Young University (BYU), located in Provo, Utah. The standards are largely derived from codes of conduct of the LDS Church and were not put into written form until the 1940s. Since then, they have undergone several changes. The CES Honor Code also applies for students attending other CES schools: Brigham Young University–Idaho, Brigham Young University–Hawaii, and Ensign College.

Every year BYU has an "Honor Week" dedicated to celebrating the legacy of the Honor Code and to remind students of the importance of following it. Early forms of the CES Honor Code are found as far back as the days of the Brigham Young Academy (1875–1903). Early school president, Karl G. Maeser, created the "Domestic Organization", which was a group of teachers who would visit students at their homes to see that they were following the school's moral rules. In the 1901 school catalog this guide of conduct included a prohibition on "strong drink and tobacco", "profanity and obscenity", attending parties not under the control of "responsible persons", "keeping late hours, having improper associates, and visiting places of questionable repute". Maeser also, however, relied largely on individual student's honor and honesty in keeping the rules, intending faculty visits as times of counsel rather than espionage. After George H. Brimhall served as president, enforcement became somewhat more lax (there were no more faculty visits), but adherence to the same basic principles were encouraged. From 1910 to 1960 the annual student catalog would only contain a few brief sentences on student conduct and discipline, often mentioning the prohibition of tobacco, "improper associates", and "visiting places of questionable repute", though the 1930s and 40s saw increased standards regarding rules related to student housing and the dress code. Women were allowed to wear slacks only on Saturdays, and men wore uniforms for a short time.

In 1949 students drafted the first Honor Code enforced by an Honor Council of students and administrators, and was used mainly for cases of cheating and academic dishonesty. The Student Honor Council, created around 1949, oversaw case violations. This council met with enough success among students in alleviating cheating that in 1957 BYU president Ernest L. Wilkinson suggested the Honor Code expand to include other school standards. This led to an expansion during the 1960s which created the bulk of what the Honor Code represents today: rules regarding chastity, dress, grooming, drugs, and alcohol. Instead of a short paragraph on university standards, the undergraduate catalog began printing a more detailed set of Honor Code policies in 1968, including a clause requiring students to act when observing any violation and a list of banned drugs ("amphetamines, barbiturates, hallucinogenic drugs, psychedelic drugs, and narcotics"). This change came because the administration completely took over the previously student run honor code and disbanded the student senate and student honor code committee. The honor code was expanded in the 1970 catalog with a requirement to adhere to the "standards of dress" and the addition of marijuana and LSD to the list of banned drugs.

In the 1960s, several rules regarding longer hairstyles in men were introduced after long hair on men became associated with the radical movements then springing up on college campuses around the country. However, long hair and beards were not completely against the rules until the mid-1970s with the 1978 annual catalog being the first edition to contain any detailed dress and grooming standards code. The 1960s also saw changes in rules regarding women's dress, as LDS Church leaders made statements against low-cut dresses and short skirts. By this time, women were allowed to wear slacks and pant-suits, but jeans were not allowed until 1981.

The CES Honor Code governs not only academic behavior but also everyday conduct on or off campus as well as dress and grooming standards of students and faculty, with the aim of providing an atmosphere consistent with LDS principles. The Honor Code requires:

Specific additional restrictions on appearance have been mentioned including those deemed as "extreme fashion" including a ban on shaved heads for women, blue hair, long nails or eyeshadow for men, and any piercings besides a single pair for women.

Before the 1960s there was little explicit mention of homosexuality by BYU administration, but by 1962 a ban on homosexual students was enacted. On 12 September 1962 Apostles Spencer W. Kimball and Mark E. Peterson and BYU President Ernest L. Wilkinson agreed on a university policy that "no one will be admitted as a student ... whom we have convincing evidence is a homosexual". They agreed to share information about individuals cases of homosexual members between general church administration and BYU administration. This policy was reiterated in Wilkinson's address to BYU in 1965 when he stated "we [do not] intend to admit to this campus any homosexuals. ... [I]f any of you have this tendency and have not completely abandoned it, may I suggest you leave the University immediately .... We do not want others on this campus to be contaminated by your presence." The 1967 version of the Honor code stated that "homosexuality will not be tolerated" along with not approving "any form of artificial birth control".

The ban on any homosexually oriented students was softened a decade later by Wilkinson's successor Dallin H. Oaks in a 19 April 1973 Board of Trustees meeting. There it was decided BYU would allow students who had "repented of" homosexual acts and "forsaken" them for a "lengthy period of time". Additionally they would allow students "guilty of irregular sexual behavior" (not including fornication or adultery equivalents) who were "repentant" and "showed evidence" that the act(s) would "not be repeated" while still banning overt and active homosexuals.