This chapter intends firstly to analyze the problem of identifying learning disabilities, from the standpoint of competing diagnostic models. The controversy between different models for identifying learning disabilities was presented, contrasting the characteristics of diagnostic models and models based on response to intervention. Second, an analysis of the main predictive factors of reading and writing was offered, using recent results from research carried out in different languages. The most often studied predictors-phonological awareness, speech perception, the alphabetic principle, rapid automatic naming, and vocabulary-were analyzed for their relationship to reading and writing. Finally, a discussion follows on the effects of certain programs that have been developed in different countries to prevent reading and writing learning disabilities.