Description of the project This study explored a case of developmental dyslexia in secondary school in a four-year longitudinal follow-up. An intervention was carried out by collecting data from the participant’s school records, applying compensatory strategies, and implementing a dyslexia-specific programme. The theoretical framework was reviewed by analysing the main causative components of this disorder, namely phonological awareness, verbal short-term memory, and naming speed. Justification was given for the need to study individual cases and to conduct a longitudinal study. A dyslexia-specific programme was implemented, including objectives, evaluation indicators, content, activities, and examples of activities. The results showed progress in the student’s development in all affected areas (phonological awareness, verbal short-term memory, and naming speed), displaying overall progress in curricular areas (Spanish, mathematics, social sciences, English, and physical education). Appropriate interventions were shown to influence people with dyslexia, leading to the conclusion that interventions should be tailored as closely as possible to the individual characteristics of subjects. These findings are discussed based on the theoretical explanations of underlying deficits in dyslexia, as well as the need for and limitations of longitudinal studies.