The law of chastity is a moral code defined by the Church of Jesus Christ of Latter-day Saints. According to the church, chastity means that "sexual relations are proper only between a man and a woman who are legally and lawfully wedded as husband and wife." Therefore, abstinence from sexual relations outside of marriage, and complete fidelity to one's spouse during marriage, are required. As part of the law of chastity, the church teaches its members to abstain from adultery and fornication.

The Church of Jesus Christ of Latter-day Saints, informally known as the LDS Church or Mormon Church, is a restorationist, nontrinitarian Christian denomination that is the largest denomination in the Latter Day Saint movement. The church is headquartered in the United States in Salt Lake City, Utah and has established congregations and built temples worldwide. According to the church, it has over 17 million members and over 99 thousand volunteer missionaries. As of 2012, the church was the fourth-largest Christian denomination in the U.S. As of 2023, the church reported over 6.8 million U.S. members.