Behavior theory has fallen from favor as a foundation for aphasia rehabilitation. Once a robust basis for experimental and clinical examination of communication disorders in adults, behavior modification has been largely absent in the literature of the past 25 years. This paper advocates a return to the application of a behavioral framework for the treatment of aphasia, with particular attention to the principles of reinforcement, and punishment, including overcorrection. It also advocates a return to such programs of instruction as melodic intonation therapy and to the application of contemporary alternate augmentative communication systems (AAC). The language of sets provides an overall framework for approaching aphasia therapy. Key Words: Programmed instruction, aphasia, rehabilitation, behavioral speech interventions Introduction Behavior theory presents a set of principles by which a person's performance can be observed, analyzed and modified to support the development of socially valued adaptive skills. These principles are rules or laws which describe behavior and its relationship to environmental consequences and motivating stimuli. It is important for speech-language pathologists (SLPs) to understand behavioral principles, because clinical treatment involves the modification of communicative behavior. When clinical treatment is effective, there is behavioral change. Principles of behavior modification have been described as they relate to aphasia rehabilitation (Brookshire, 1969; Goldfarb, 1981; Holland, 1970; Holland & Harris, 1968). These principles refer to a Skinnerian or operant model, not a Pavlovian or reflexive model. Systematic reinforcement of operant behaviors can lead to new responses that expand a person's interactive repertoires communicatively, socially, and verbally. New reflexes cannot be learned, but operant procedures can be used to inhibit or shape infantile oral reflexes, such as suckling and biting, which may be exhibited following brain damage in adults. While there was a flurry of activity in operant-based aphasia research more than 25 years ago (Albert, Sparks, & Helm, 1973; Brookshire, 1968; Goldfarb & Scharf, 1980; Keenan, 1966; Keith & Darley, 1967; Rosenberg & Edwards, 1965; Sarno, Silverman, & Sands, 1970; Tikofsky & Reynolds, 1962; 1963), there has been much less recent interest. One recent non-language study (Goldenberg, Hodges, Hershe, & Jinich, 1980) reported efficacy of operant conditioning in reducing fecal incontinence in 12 patients (ages 12-78 years) with medical and surgical conditions using biofeedback. An auditory language comprehension program for persons with severe aphasia (Bastiaanse, Nijboer, & Taconis, 1993) was applied in a case study involving a participant who learned to discriminate a target word from one, two, and then three distracters. Two other studies used filmed or videotaped programmed instruction to examine reading recognition and comprehension (Di Carlo, 1980) and comprehension of indirect requests such as "can" and "should" (Levey & Goldfarb, 2003) with participants who had aphasia. However, the generalizability of recent studies is limited due to the small number of subjects and low statistical power. Consequences of Ignoring Behavioral Principles SLPs with a limited understanding of applied behavior analysis (ABA) are at risk for attempting to modify maladaptive communicative behavior ineffectively. Consider the following vignette: Several adults with aphasia are seated in a small group during a speech-language therapy session. One of the adult clients points to the door and says, "Go, go." When this request is ignored by the SLP, the client repeats the gesture and the utterance with greater intensity. Without turning to the client, the SLP says, "Just a minute, I'm helping John now." The client then unlocks his wheelchair and rolls back and forth, ramming the chairs of other group members. …