Autism is a severe disruption of normal developmental processes that occurs in the first three years of life. It is manifested in impaired language, cognitive, social and adaptive functioning. These essential skill deficits cause children to fall progressively farther behind their typical peers as they grow older. The cause is unknown, but evidence points to physiological and neurological abnormalities.

Children with autism generally do not learn in the same way that children normally learn, because, in part, they lack the fundamental skills which enable them to acquire and process basic information. They appear to lack understanding of simple verbal and nonverbal communication, are often affected by sensory over-stimulation or under-stimulation, and seem withdrawn in varying degrees from people and the world around them. They are often preoccupied with certain activities and/or objects, which further interferes with their ability to acquire skills and learn from information that is available to them. These difficulties result in significant delays in their development of language, play and social skills, including their failure to notice and learn through imitation of their peers.

Despite the disruption of typical learning processes, behavioral scientists have utilized principles and procedures of learning theory to develop effective treatment methodologies for teaching children with autism. Four decades of research conducted by Dr. Ivar Lovaas and his associates at UCLA, as well as other behavioral researchers, have empirically demonstrated the effectiveness of intensive behavioral treatment for children with autism. In particular, early intervention can significantly improve the abilities of these children to learn and function more adaptively. In his 1987 follow-up study, Dr. Lovaas reported that 17 out of 19 children, who received intensive behavioral treatment, significantly improved their social, self help, play and communication skills, including the development of functional speech. Furthermore, 9 of the 19 children were able to successfully complete first grade in regular education classes and were indistinguishable from their peers on measures of IQ, adaptive skills, and emotional functioning. A 1993 followup study by McEachin, Smith and Lovaas showed that treatment gains were maintained more than six years later and eight of the children continued to progress in regular education classes without support.

The children in this study were three years old and younger when treatment was started. They received an average of 40 man-hours per week (some received more that 40 hours, some received less) of individual treatment provided by UCLA undergraduates who were supervised by graduate students and psychologists. Treatment lasted an average of two years or longer.

Applied Behavior Analysis (ABA) with autistic children has experienced a return to popularity over the past six years. This renewed interest, in large part, can be linked to the publication of Catherine Maurice's book, Let Me Hear Your Voice, in which she chronicles the treatment of her two autistic children. Like many professionals and parents, Ms. Maurice initially had a dim view of behavioral intervention. She believed it to be an extremely negative and inflexible procedure. Moreover, she thought that behavioral intervention had limited effectiveness and often produced overtly mechanical responding in children. Her experience, however, proved to be far different. She found that behavioral intervention can be employed positively with a high degree of flexibility. Most importantly, the intervention proved to be highly effective.

Ms. Maurice's story gave hope to parents who had been led to believe, often by professionals, that autistic children will always remain severely impacted by their diagnosis. With hope and a direction, parents throughout the world started setting up intensive behavioral programs. Parents also started demanding that schools and state agencies use ABA with their children.

Although the tremendous popularity of ABA is recent, ABA is not a new procedure. Critics of behavioral intervention often contend that it is an "experimental" procedure with limited empirical evidence of its effectiveness. Lovaas (1987) and McEachin, Smith and Lovaas (1993) are often cited as the only two investigations to show that behavioral intervention with autistic children is effective. In fact, ABA is based upon more than 50 years of scientific investigation with individuals affected by a wide range of behavioral and developmental disorders. Since the early 1960's, extensive research has proven the effectiveness of behavioral intervention with autistic children. The research has shown ABA to be effective in reducing disruptive behaviors typically observed in autistic individuals, such as self-injury, tantrums, non-compliance and self-stimulation. ABA has also been shown to be effective in teaching commonly deficient skills such as complex communication, social, play and self-help skills. As early as 1973 Lovaas and his colleagues published a comprehensive study showing ABA to be effective in treating multiple behaviors with multiple children.

Although the work by Lovaas is the most frequently cited, there is other evidence that ABA can result in substantial benefit. Harris and Handleman (1994) reviewed several research studies that showed that more than 50% of autistic children who participated in comprehensive preschool programs using ABA were successfully integrated into non-handicapped classrooms, with many requiring little on-going treatment.