Dr. Orton, who was fascinated by the phenomenon of reversals, came to believe that reading difficulties, or "word blindness," were caused by neurological factors. He started out by studying the brains of World War I veterans who had suffered head injuries, and he began to map out the location of language function in the brain. In 1925, he delved into the topic of dyslexia upon studying a 16-year-old who despite normal intelligence had not learned to read. Over the next two years, he ran a summer program in which these types of children were taught phonics using a visual-auditory-kinesthetic approach, adapted to meet their individual needs. For the next 20 years, he and his wife, June Lyday Orton, continued to conduct research and taught others these techniques, who in turn taught others until clinics, private schools, and summer camps using this approach were established all over the country. After her husband’s death, June continued their work and later became president of The Orton Society.

Anna Gillingham began to consult with Dr. Orton in 1929. In 1934, she and a fellow teacher, Bessie Stillman organized Orton’s remedial techniques into a manual for teachers, which is now the familiar green manual. They also established a remedial program at the Punahou School in Honolulu. Starting in 1947, Anna Gillingham traveled around setting up teacher training programs and provided tutoring for dyslexic students. In addition, she set up a program in which "at risk" kindergartners were placed in a first grade class that was taught by a specially trained teacher using a phonetic, multisensory approach with cursive writing from the beginning. In 1962, Sally Childs, her professional heir, carried on her mission of training teachers, and later, went to England and with Marion Welchman established the British Dyslexia Society.

Today, we have the International Dyslexia Association (formerly The Orton Society) and the Academy of Orton-Gillingham Practitioners and Educators (established in 1994) with the goal being that no child should remain undiagnosed, and that teaching should start early, be commensurate with a child’s learning style, and continue for as long as is necessary.