Presents data supporting the hypothesis that threats of shame, a self-imposed punishment, and threats of embarrassment, a socially imposed punishment, function much like threats of state-imposed legal sanctions to reduce the expected utility of illegal behavior and, thus, to increase the likelihood of compliance with the law. 346 adults were interviewed in 1982, 5 yrs prior to the start an anti-littering campaign, and 324 Ss were interviewed in 1989, 2 yrs after the campaign began. In 1982, 39% of the Ss indicated they probably would litter in the future, compared to 31% in 1989. In 1982, 37% strongly agreed that they would feel guilty if they littered, compared to 67% in 1989. Also, in 1982, 8% believed they definitely would lose the respect of others if they littered, compared to 21% in 1989.