External reinforcement paradigms are useful and necessary in a complete instructional system and external reinforcement is not antithetical to a belief in an intrinsic motivation hypothesis. Teacher training, parent education, and classroom management, as well as complex learning sequences, can be improved by the use of principles emerging from the experimental analysis of behavior. Teachers especially need to pay attention to all the variables which mediate their effectiveness with children. It is time to interrelate learning and developmental principles from differing points of view which have met the empirical test of effectiveness. On the whole, the approach to instruction required by the systematic use of external reinforcement can strengthen systems derived from other theories. (WY)