The goal or this research is to identify the tasks with the highest predictive power yusing a Multidimensional Longitudinal Approach within a prevention-oriented RtI model. The assessment of genetic family risk, early linguistic and cognitive skills on Spanish literacy acquisition and learning difficulties was carried on in two cohorts of 850 4-7 and 3-6 year-old-children. Results show that phonological skills are predictive from the beginning of the assessment, reading abilities take relevance later on, and then other components as aritmetics or motor skills take place.