Introduction: The present study provides description of two typologically diverse languages in origin (Slavic vs. Latin), script (Cyrillic vs. Roman), and internal structure. One of the similarities, between the two studied orthographies is that spelling-sound transparency is quite consistent in both languages. The goal of the present study was to offer a comparison of learning to read in these languages. Specifically, the study compared the importance of several predictors in the development of reading among children learning two consistent orthographies (Bulgarian and Spanish). Method: A total of 157 children, native speakers of Bulgarian (n = 80) and Spanish (n = 77),were recruited from three public schools (one in Sofia and two in Madrid) located in middle class areas. Correlational and regression analyses revealed that Bulgarian and Spanish datawere fitted by the same predictors of passage reading efficiency and reading speed. Results: The analyses showed that RAN-Letters played an important role in predicting reading fluency and passage reading efficiency among children in both languages. In addition, vocabulary appeared to be a core component skill of reading comprehension, which was equally important for learners of both orthographies. Results showed that when equivalent reading predictors are assessed, the core components of fluency and higher level literacy skills (reading comprehension) appear to be very similar in both consistent orthographies. Discussion and Conclusion: Theoretical and educational implications that highlight the importance of RAN and Vocabulary assessment and intervention in the first primary school years are discussed.