"Just Say No" was an advertising campaign prevalent during the 1980s and early 1990s as a part of the U.S.-led war on drugs, aiming to discourage children from engaging in illegal recreational drug use by offering various ways of saying no. The slogan was created and championed by Nancy Reagan during her husband's presidency.

The war on drugs is the policy of a global campaign, led by the United States federal government, of drug prohibition, military aid, and military intervention, with the aim of reducing the illegal drug trade in the United States. The initiative includes a set of drug policies that are intended to discourage the production, distribution, and consumption of psychoactive drugs that the participating governments, through United Nations treaties, have made illegal.