Social Norms Effectiveness

Several years ago researchers at the University of North Carolina administered breathalyzer tests to students returning home at night. They found that on traditional party nights (Thursdays through Sundays) two of every three students returning home had no measurable blood alcohol concentration (BAC).

The researchers then widely publicized their findings, calling their campaign “2 out of 3, zero BAC.” As the message got out and students realized that their perceptions of drinking on campus had been greatly exaggerated and that they didn’t need to drink or to drink heavily to “fit in,” drinking dropped.

Between 1999 and 2002, the proportion of students with any alcohol in their bodies declined by 15%. Those with BAC’s higher than .05 dropped 23%, or nearly one-fourth. And the average number of drinks consumed over the course of an evening fell from 5.1 to 4.3.

The research was led by Dr. Robert Foss of the University of North Carolina at Chapel Hill’s Highway Safety Research Center.


  • Strand, E. The illusion of college drinking. (College drinking may be legendary, but the drunken student stereotype seems to be a myth). Psychology Today, October, 2003. (