Behavior can be modified because it is governed by its consequences. Observable behavior, excluding its causes, is modified by the application of techniques derived from B.F. Skinner's operant learning theory. Optimum effects can be achieved only after thorough knowledge of the child is gained, particularly in the area of his capabilities. The reinforcers which influence the child must be discovered by observation. A positive reinforcement schedule is then employed, rewarding the desired behavior in various ways. Shaping may be used, in which partial or approximate behaviors are rewarded until the actual desired behavior occurs. Decreasing undesirable behavior occurs when an incompatible desirable behavior is shaped by: (1) securing the desired response, (2) shaping small segments of the desired behavior, (3) using a high reinforcement ratio, and (4) gradually decreasing the reinforcement. The concept of contingent results must be clearly understood. A case study is given in which operant learning theory is applied to modify the behavior of a seventh grade boy. (AE)