A primary goal of many researchers in the field of literacy development is to help those who have reading difficulties to learn to read better. This chapter focuses on those children who have particular difficulties in learning to read. Various labels have been used to describe particular reading problems, including dyslexia, reading disability, or specific reading retardation. Historically, children with apparently specialized problems in reading have been of great interest to clinicians, teachers, and researchers. Early definitions of specific developmental dyslexia focused on three factors that distinguished a dyslexic from a typical poor reader. Dyslexic children were defined (Snowling, 2000) as poor readers who:

1. had had adequate instruction in reading 2. had had ample sociocultural opportunities 3. had normal intelligence.