Improvement of knowledge about the cognitive mechanisms involved in skilled reading and reading acquisition contributed to the development of new tools for the assessment of reading disability. A first step of the assessment focuses on the efficacy of the global and analytic reading procedures. Evidence for disharmonious development of these procedures then requires investigating the cognitive mechanisms involved in their establishment. Phonological processing skills are then typically assessed because of their well-known impact on reading acquisition. Recent findings have shown that the integrity of another cognitive mechanism, the visual attention span, was also required for the normal development of the reading system.