Reality therapy, developed by William Glasser, rejects the concept of mental illness (i.e. therapists would not bill using the DSM-5 because they don't believe in the pathology model). Reality therapy revolves around the idea that individuals have psychopathology because they can not control their environment in a way that satisfies their basic needs for survival, belonging, power, fun, and freedom.

According to reality therapy, individuals have two psychological needs: the need to love and to be loved and the need to feel worthwhile to themselves and to others.

The reality therapist believes that each individual has a "success" or "failure" identity; reality therapy encourages the client to face reality with no excuses or explanations.

Reality therapy proceeds on the theory that the brain functions as a system that controls behavior by fulfilling needs built into the environment; an individual's problems are caused by not being able to control or effectively act on these environmentally based needs. Reality therapy seeks to help clients choose actions appropriate to satisfying basic needs of survival, reproduction, power, freedom, and fun.

In this model, behavior is an integration of a person's feelings, thoughts, and actions relating to personal needs and the behavior of others; this behavior comes from within and depends on the needs it means to satisfy. Since its focus is on present experience and helping the client to make better choices of behavior, reality therapy considers antecedent experiences and outside forces to be of little import. Every person, along with society, is assumed to have a set of personal standards, which reality therapy considers especially important if a client is operating contrary to those personal or societal standards. Reality therapy seeks to teach people to gain control of their environments by choosing more effective behaviors. This lesson is a therapeutic exercise in helping individuals reach greater fulfillment of their needs.