In the preceding chapters, we discussed the process of learning to read. As we pointed out there, despite some variation in teaching methods and cultural approaches to teaching reading, most children do learn to read quite well. However, some children do not do particularly well in reading and, more seriously, some grow to adulthood without obtaining fluency in reading. As we shall see in a moment, part of the problem can be traced to general cognitive abilities since there is a strong correlation between reading achievement and a child's score on an intelligence test. This isn't the whole story, however, since there are some people who, despite average or above average scores on intelligence tests, do not read well (or at all, in some cases). But we're getting ahead of ourselves a bit. We will begin this chapter by discussing the relative frequency of reading problems. We will then discuss in order: poor reading, acquired dyslexia, and developmental dyslexia. The term dyslexia is used to describe individuals with normal to high intelligence who have severe reading problems. In the case of acquired dyslexia, the disability is due to some type of known brain damage, while in developmental dyslexia there is no identified brain damage.