Throughout the scientific literature shows that studies evaluating the effectiveness of school-based substance abuse prevention programs have used a wide range of intervention agents. Nevertheless, in Spain, the school-based programs in daily practice, the vast majority, are applied only by regular classroom teachers of schools. In this regard, some research suggests that the variable type of applicator affects the effectiveness of school-based programs for drug prevention. This article presents a review of studies comparing the results obtained in the school-based programs when applied by regular classroom teachers to other external contributors. Taken together, the results of the reviewed studies are contradictory and, therefore, the evidence is not conclusive. However, it highlights the moderating role of the variable
type of monitor on the effects of programs. Finally, it is recommended to lead studies to evaluate the specific characteristics or skills that must have an effective monitor as the training can contribute to its acquisition or improvement.