fects of programs on the harmful consequences of drug use or drug dependence, for the reasons mentioned above.

Positive effects of prevention programs have been reported on all three types of self-report measures. For example, in the meta-analysis of school-based prevention programs by Gottfredson et al. (forthcoming), roughly a third (36 percent) of the studies that included any measure of substance use included only prevalence measures; another third (32 percent) included only frequency measures. A smaller number (6 percent) included only variety measures, and 20 percent included some combination of these types of measures.

In the committee’s view, these distinctions among the many possible outcomes of prevention programs should be the subject of serious debate and study. The field has not yet developed a consensus about which outcome or outcomes are important and reasonable to expect from prevention programs. Currently, differences across prevalence and frequency measures are glossed over in reports about the effectiveness of prevention. Whether a program works to delay onset for a week or a month, to limit the number of different drugs tried, to reduce the amount consumed per occasion, to prevent dependence, or to limit the harmful consequences of use has not been the focus of prevention studies. Only by encouraging research that includes the entire array of outcome measures and by reporting separately on each can the field move toward an understanding of the dimensions of use that are and are not influenced by various types of prevention programs. This information could then be evaluated according to the value placed on each outcome. Because certain of the outcomes of potential interest (e.g., dependence, harmful consequences) come into play years after a prevention program is over, this recommendation also implies that prevention research should include longer-term follow-up periods.

Features of the Most Effective Prevention Strategies

Botvin’s (1990) summary of the effectiveness of different kinds of prevention programs has become influential in the prevention field. According to Botvin, four general approaches are largely ineffective for reducing substance use: “information dissemination” approaches, which teach primarily about drugs and their effects; “fear arousal” approaches, which emphasize the risks associated with tobacco, alcohol, and drug use; “moral appeal” approaches, which teach students about the evils of use; and “affective education” programs, which focus on building self-esteem, responsible decision making, and interpersonal growth. Approaches that do reduce substance use include resistance-skills training, which teaches students about social influences to engage in substance use, and specific

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