Just Say No was a television advertising campaign, part of the War on Drugs and prevalent during the 1980s and early 1990s, to discourage children from recreational drug use by offering various ways of saying "no." Eventually, this also expanded into the realm of "Just say no" to violence, premarital sex, and any other vices that young people might try. The slogan was championed by Nancy Reagan.
"Just Say No" also crossed over to the UK, where it was popularised by the BBC's 1986 "Drugwatch" campaign, which revolved around a heroin-addiction storyline in the popular children's TV drama serial Grange Hill. The cast's cover of the original US campaign song, with an added rap, reached the UK top ten.
The campaign even made its way into popular American culture as TV shows like Diff'rent Strokes and Punky Brewster produced episodes centered around the campaign. In 1987, La Toya Jackson became spokesperson for the campaign and recorded a song entitled "Just Say No" with British hit producers Stock/Aitken/Waterman, but changes in her public persona to a sexier style over the next few years limited her further involvement in the campaign.
The campaign drew some criticism for underestimating the drug use in America and reducing its solution to a catch phrase. Over time, the campaign became the subject of some satire. No significant reduction in the use and trafficking of illegal drugs was seen during the height of the campaign and it is arguable that drug use has significantly grown since, although it has been argued the campaign may have stopped a lot of people from considering taking drugs in the first place.
Ironically many of the child stars involved in the campaign, like Drew Barrymore and Corey Feldman, were at the time or later illegal drug users.