This study investigated predictors of word reading and reading comprehension skills using longitudinal data from Spanish-speaking kindergartners (N = 163) and first grade students (N = 305) from high SES families in Chile. Individual differences in letter-naming fluency and phonemic segmentation fluency, but not vocabulary, were positive predictors of word reading, over time, for kindergartners. Furthermore, kindergartners with higher letter-naming fluency and phonemic segmentation fluency had a faster rate of change in word reading over time. For first graders' reading comprehension, word reading, nonsense word fluency, and vocabulary were positively and uniquely related. However, the rate of change in the reading comprehension outcome differed over time by children's level of vocabulary, nonsense word fluency, and word reading. These results suggest that code-related skills are important for word reading, but vocabulary might not have a direct, unique relation with word reading in a transparent orthography. In addition, phonological decoding fluency appears to contribute to reading comprehension even over and above word reading accuracy in Spanish.