This paper sets out to clarify the unique features of exercise addiction. It begins by examining how this addiction can be distinguished from compulsions and impulse control disorders both of which, like an addiction, involve excessive behavior that creates adverse effects. Assessment of exercise addiction also requires that clinicians be attuned to other forms of excessive behavior, especially eating disorders that can co-occur with exercise. Finally in an effort to clarify exercise addiction, this paper uses the four phases of addiction to examine the attributes of exercise that define it as a healthy habit distinct from an addiction. The paper ends with a discussion of the implications of these topics for effective assessment and treatment.