Dyslexia refers to difficulties with accurate and/or fluent reading, despite adequate cognitive ability and opportunity to learn to read. Dyslexia is a heterogenous disorder: multiple neurocognitive risk and protective factors interact to produce specific patterns of reading difficulties. There are two distinct groups of adults with Dyslexia: Accuracy-Improved and Persistently-Poor readers. Both groups have reading difficulties during childhood, and persistent fluency and phonological deficits in adulthood. However, while Accuracy-Improved readers achieve average single word reading and spelling skills by adulthood, Persistently-Poor readers show enduring word reading and spelling deficits. The reasons for these different reading outcomes among individuals with Dyslexia are not yet fully understood. There is evidence that visual attention difficulties may play an essential role in Dyslexia. Visual spatial attention is the set of neurocognitive mechanisms responsible for selecting information at certain locations in a visual scene (such as a portion of text) for detailed processing while filtering out other information. Two aspects of visual spatial attention have been implicated in reading and Dyslexia: attentional orienting, which refers to shifting the attentional focus from one location to another, and attentional focusing, which refers to expanding or contracting the breadth of the attended region. However, it is not yet fully understood how these attentional processes are impaired in Dyslexia, and how impairments contribute to specific patterns of reading difficulties. The overarching aim of the current thesis was to examine differences in visual spatial attention between Accuracy-Improved and Persistently-Poor readers. [...]