The main sources of ineffectiveness are the failure to distinguish between alternative prevention objectives and target groups, the failure to use existing research pointing to the need to change attitudes and behaviors as well as knowledge, and lack of attention to the rewards and reinforcements associated with drug use. In addition, they have failed to make the necessary links between the reality of the classroom and the reality outside the classroom, have not accounted for interpersonal influences, and have lacked links with other areas of the school curriculum. Moreover, they have received too little time, have usually not been evaluated appropriately, and have been inadequately implemented. Changes needed include clear specification of objectives, realistic objectives, honest presentations of both the costs and benefits of drug use and nonuse, and attention to the broader range of reinforcements involved. Programs should also make explicit links between classroom skills and the reality outside the classroom, rest on sound and explicit theoretical bases, and be carefully implemented and evaluated.