There is resounding evidence of the existence of direct precursors of written language, most specifically phonological awareness, letter knowledge, vocabulary, and oral comprehension. The initial differences identified in the development of written language precursors are directly related to subsequent students' academic trajectories. Socioeconomic status is a significant source of initial differences in performance, with discrepancies in the development of reading precursors favoring children from more affluent backgrounds. We assessed reading precursors in 176 Chilean children from different socioeconomic levels. Significant differences in performance were found, which tended to favor the higher socioeconomic groups for each precursor we tested. However, the developmental trajectories of skills were similar for phonological awareness, letter knowledge, vocabulary, and oral comprehension. A compensatory trajectory was observed only in the case of rapid naming. The problem arises from the need for educational systems to adapt to the specific needs of their students, in order to generate compensatory trajectories in all reading precursor skills and enable a decrease in the gaps in reading performance among children from different socioeconomic backgrounds.