ABC: Antecedent, Behavior, Consequence

This educational strategy seeks to mold student behavior

The Antecedent precedes the behavior.
Getty Images - Pedro Blanco

ABC—also known as antecedent, behavior, consequence—is a behavior-modification strategy often used with students with disabilities, particularly those with autism, but it can also be useful for nondisabled children. ABC seeks to use scientifically tested techniques to help guide the student to a desired outcome, whether that be extinguishing an undesirable behavior or fostering good behavior.

ABC Background

ABC falls under the umbrella of applied behavior analysis, which is based on the work of B.F. Skinner, also known as the father of behaviorism.

Skinner developed the theory of operant conditioning, which uses a three-term contingency to shape behavior: stimulus, response, and reinforcement. 

ABC, which has become accepted as a best practice for evaluating challenging or difficult behavior, is almost identical to operant conditioning, except that it frames the strategy in terms of education. Instead of a stimulus, you have the antecedent; instead of the response, you have the behavior, and instead of the reinforcement, you have a consequence.

The ABC Building Blocks

To understand ABC, it's important to take a look at what the three terms mean and why they're important:

Antecedent: The antecedent refers to the action, event, or circumstance that occurred before the behavior. Also known as the "setting event," the antecedent is anything that might contribute to the behavior. It may be a request from a teacher, the presence of another person or student, or even a change in the environment.

Behavior: The behavior refers to what the student does and is sometimes referred to as "the behavior of interest" or "target behavior." The behavior is either pivotal (it leads to other undesirable behaviors), a problem behavior that creates a danger for the student or others, or a distracting behavior that removes the child from the instructional setting or prevents other students from receiving instruction.

Behavior needs to be described in a way that is considered an "operational definition" that defines the topography or shape of a behavior in a such a way that two different observers can identify the same behavior.

Consequence: The consequence is an action or response that follows the behavior. The "consequence" is not necessarily a punishment or form of discipline, though it can be. Instead, it is the outcome that is reinforcing for the child, very similar to the "reinforcement" in Skinner's operant conditioning. If a child screams or throws a tantrum, for example, the consequence may involve the adult (the parent or teacher) withdrawing from the area or having the student withdraw from the area, such as taking a timeout.

ABC Examples

In nearly all psychological or educational literature, ABC is explained or demonstrated in terms of examples. The table illustrates examples of how a teacher, instructional assistant, or other adult might use ABC in an educational setting.




The student is given a bin filled with parts to assemble and asked to assemble the parts.

The student throws the bin with all the parts onto the floor.

The student is taken to timeout until he calms down. (The student later picks up the pieces before he is allowed to return to classroom activities.)

The teacher asks a student to come to the board to move a magnetic marker.

The student bangs her head on the tray of her wheelchair.

The teacher goes to the student and attempts to redirect and soothe her with a preferred item (such as a favored toy).

The instructional assistant tells the student, “Clean up the blocks.”

The student screams, “No! I won’t clean up.”

The instructional assistant ignores the child’s behavior and presents the student with another activity.

ABC Analysis

The key to ABC is that it gives parents, psychologists, and educators a systematic way to look at the antecedent or precipitating event or occurrence. The behavior, then, is an action by the student that would be observable to two or more people, who would objectively be able to note the same behavior. The consequence might refer to removing the teacher or student from the immediate area, ignoring the behavior, or refocusing the student on another activity, one that hopefully won't be an antecedent for a similar behavior.