The aim of this study was to understand whether the reading comprehension process is better explained by a single or by multiple factors. 184 students (9 to 13 years old) were presented with a recently devised battery of tests, that measure ten aspects of reading comprehension. Structural equation modelling showed that a two factors model better accounts for the data compared to a one or a three factors model. Results confirmed the hypothesis which distinguishes between "basic" and "complex" aspects of reading comprehension. The second goal of the study was to analyze the relationship between the two-components model and scholastic achievement. Our results highlighted that the more "complex" aspects of reading comprehension, reflecting some metacognitive knowledge and control processes, are the better predictors of scholastic achievement.