Orton-Gillingham and Orton-Gillingham-based reading instruction: a review of the literature.

Orton-Gillingham (OG) and Orton-Gillingham-based reading instructional programs are commonly implemented reading programs in the United States. Twelve studies that employed quasi-experimental or experimental designs are reviewed. These studies included elementary students, adolescents, and college students. Of the 12 studies, 5 reported that the OG instruction was more effective than were comparison or control interventions for all measured outcomes, 4 reported that the OG instruction was more effective for at least 1 (but not all) outcomes in comparison to other intervention(s), 2 reported that the alternate instruction was more effective than the OG instruction, and 1 reported no significant differences once covariates were included. The largest effects were reported for word attack and non-word reading outcomes, with mean effect size of .82, and comprehension outcomes, with a mean effect size of .76. Following a summary of each study, limitations of the current review and implications for future research and practice are described. Given the small number of studies, the lack of methodological rigor of the existing studies, and the inconclusive findings of the effectiveness of OG programs, additional research is needed before the scientific basis can be established.

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In the early part of the 20th century, the field of learning disabilities was still in its infancy. At that time, Dr. Samuel Orton, a child neurologist, estimated that approximately 10% of the school population had reading disabilities and speculated that reading problems were caused by neurological deficits. Orton's early conclusions formed two major tenets of the characteristics of dyslexia: (a) reading problems were caused by strephosymbolia (or twisted symbols), and (b) a lack of brain hemisphere dominance caused information to be processed in both hemispheres, resulting in mirror images (e.g., reversals of the letters b and d).

Although Orton's speculated causes of reading disabilities have not stood the test of time (phonological processing problems are currently accepted as the primary cause of reading disabilities), his ideas about appropriate reading instruction have. Specifically, Orton (1937) stated that the instructional approach should

 
   attempt to capitalize [sic] their [students'] auditory 
   competence by teaching them the phonetic equivalents 
   of the printed letters and the process of blending 
   sequences of such equivalents so that they might 
   be able to produce for themselves the spoken form 
   of the word from its graphic counterpart. (p. 159) 

The instructional approach conceived by Orton was developed into a curriculum by Anna Gillingham and Bessie Stillman and first described in the manual Remedial Training for Children with Specific Disability in Reading, Spelling, and Penmanship (1960). Currently in its eighth edition (Gillingham & Stillman, 1997), the manual remains the backbone of Orton-Gillingham (OG) instructional programs and other instructional programs derived from the original curriculum.

Characteristics of OG-Based Instruction