A reaction to Sowell's book raises issues about behaviorally based diagnoses, stressing that developmental disorders are behaviorally defined dimensions along a continuum with no crisp partition between normalcy and disorders. It sees developmental disorders as usually the expression of extremely complex, multigenic influences on brain…

This article discusses the successes of behavior analysts in affecting challenging behaviors in persons with developmental disabilities. Three future issues are then addressed: the development of challenging behaviors, the role of rule-governance in challenging behavior, and the behavior of persons who directly apply functional assessment and…