Applied behavior analysis (ABA) is best known for its success in treating individuals with autism spectrum disorder (ASD) and other developmental disabilities (e.g., Down syndrome, intellectual disabilities). Treatment in this area is effective across an individual’s lifespan (i.e., childhood, adolescence, adulthood). In young children with developmental disabilities such as ASD, the goal of intensive, comprehensive intervention is to improve cognitive, language, social, and self-help skills. Decades of research have shown that intensive ABA treatment is the most successful approach for children with autism, and it is widely recognized by a number of sources including the U.S. Surgeon General, the American Academy of Pediatrics, and the National Institute of Mental Health. When applied to older individuals, ABA involves teaching behaviors essential to functioning effectively in the home, school, and community.