A Skinner box is a device invented around 1930 by behavioral scientist B. F. Skinner of Harvard University. The Skinner box is used in a laboratory setting to study classical conditioning and operant conditioning in animals. Skinner and other behaviorists object to the term "Skinner box" and more often call the device an operant conditioning chamber.

Behaviorism is a branch of psychology that has to do with learned behaviors. In classical conditioning, a conditioned stimulus is joined with an unconditioned stimulus, with the result that a natural unconditioned response becomes associated with the conditioned stimulus, thereby becoming a conditioned response. In the famous example of Pavlov's dog, the dog heard a bell ring just before each meal and eventually came to salivate at the sound of a bell rather than at the appearance of food.

In operant conditioning, the subject's behaviors are reinforced by desirable results, punished by undesirable results, or extinguished by having no result. Reinforced behaviors will occur more frequently, while punished and extinguished behaviors will be performed less often. An example of operant conditioning is a rat learning to navigate a maze more quickly and efficiently after a number of attempts.

A Skinner box, used to study these concepts, is a box that houses an animal and offers both unconditioned and conditioned stimuli — such as colored lights and food, respectively — and response levers or keys that serve to monitor the animal's behavior. For example, a Skinner box may be used to test classical conditioning in a bird by associating a red light with each feeding, eventually causing the bird to peck not only at food, but upon seeing the red light. A Skinner box may be fairly simple, with only one lever or key, or it may be quite complex, with a variety of stimuli and ways of monitoring response. The Skinner box has received criticism because it does not capture every nuance of the animal's behavior; pushing the lever with a nose or a paw registers as the same response, for example, and light touches of the lever may not be recorded.

B. F. Skinner has been accused, notably by author Lauren Slater and by the Church of Scientology, of raising his daughter in a Skinner box, leading to her mental illness and suicide, but this is untrue. Skinner designed a special air-crib intended to make childcare easier, but he did not conduct psychological experiments on his daughter or abuse her. Deborah Skinner Buzan, Skinner's daughter, is still alive and has refuted every point of these rumors.