Innovative models for education are often quickly adopted. Behavior modification, or operant conditioning, is an example of a technique which has been widely used because, when properly applied in the classroom, it "works." However, the application of a technique should be carefully thought through in terms of the meaning of the behavior in question. For example, three children may exhibit the same disruptive behavior, or phenotype. Yet the geneses, or genotypes, of the behavior may be very different. The child may have learned this behavior through reinforcement at home or at school; the behavior may be an expression of an emotional injury; it may indicate a lack of social skill or knowledge of alternative ways of response; or there may be other causes. For all genotypes, behavior modification may be successful in changing undesirable behavior, but it does not always address itself to the underlying cause of behavior. A paradigm is given showing possible phenotype/genotype/treatment relationships. (Author/NH)