Since dyslexia was first described in the British Medical Journal in 1896, there has been debate about the definitions and diagnostic procedures used, with some casting doubt on its very existence. However, there is now a considerable body of research regarding the nature and characteristics of this relatively common learning disorder. The contemporary view of dyslexia has emerged from a century of research in medicine, psychology and more recently neuroscience, and we now understand enough about this learning disorder to guide policy and practice. This Very Short Introduction provides an accessible overview of this exciting field of research, beginning with its history, and drawing on testimony from people living with dyslexia. Considering the potential causes of dyslexia, and looking at both genetic and environment factors, Margaret Snowling shows how cross-linguistic studies have documented the prevalence of dyslexia in different languages. Discussing the various brain scanning techniques that have been used to find out if the brains of people with dyslexia differ in structure or function from those of typical readers, Snowling moves on to weigh up various strategies and interventions which can help people living with dyslexia today.