Phonological awareness and knowledge of letters have been considered the most powerful predictors of learning to read in alphabetic writing languages, and therefore preschool education has paid great attention to promoting these skills. However, this does not seem sufficient to reduce the number of children who have difficulty learning to read. Based on the assumption that reading is essentially a cognitive and linguistic activity, Piaget's assumptions, namely the role of logical operations, have been taken up in order to analyse their relative contribution to learning to read. Thus, the main objective of this work was to identify the relative and independent contribution of three predictors - piagetian logical operations (seriation, classification and inclusion of classes), phonological awareness and knowledge of letters - to the learning of reading (in the decoding or identification of written words and in the understanding or extraction of the meaning of the text) in the early years of schooling.