This dissertation is concerned with the syndrome pure alexia, and how it may be characterized and understood. The selective impairment of reading in the context of intact writing and language has long intrigued both cognitive and clinical researchers. There is, however, no consensus about the cognitive (or cerebral) cause of the syndrome: After 40 years of research within cognitive neuropsychology, the core deficit in pure alexia is still elusive. This dissertation contains nine original articles. These address different hypotheses about the core cognitive deficit(s) in pure alexia, and how we may measure and understand this impairment. The conclusion of the dissertation is that pure alexia – although being a relatively simple syndrome – has been ill defined in the literature. This lack of stringency may have contributed to the relatively little progress made in the understanding of the pure alexia over the last two decades. Finally, two central questions in pure alexia research are discussed, and a novel hypothesis about the cognitive cause of pure alexia suggested.