Rates of cigarette smoking and smoking-related beliefs in 1980 and 2001 among 7th-11th graders in a midwestern community were compared. Smoking was less prevalent in 2001 than in 1980, with the greatest declines in experimental smoking and a smaller drop in regular smoking. Beliefs about smoking generally became more negative. Adolescents (particularly nonsmokers) viewed smoking as more addictive and as having more negative social consequences in 2001 than in 1980 and had more negative attitudes toward smoking in 2001. These results were replicated among parent-child pairs in which parents were measured when they were adolescents between 1980 and 1983 and their children were measured in 2001. These beliefs and attitudes partially mediated the effects of time on smoking.