This booklet is about changing human behavior in everyday settings in the school and home. The approach to human behavior outlined is called "behavior analysis," which is based on that approach to psychology called the exerimental analysis of behavior. The ABC model of behavior is explained. In this model, the A refers to the "antecedent" that occasions or cues the behavior, B refers to the "behavior" itself, and C refers to a "consequent" event that increases the likelihood of the behavior occurring again. An outline is presented of a general plan for changing behavior. Illustrating how the plan works in practice, behavior analysis principles are applied to three cases: a child who acts aggressively (a behavioral excess), a student said to be unmotivated (a behavioral deficit), and an unruly class (a group management problem). (JD)